(a) This subpart describes the provisions related to an exemption from the tampering prohibition in Clean Air Act section 203(a) (42 U.S.C. 7522(a)) for light-duty vehicles, light-duty trucks, medium-duty passenger vehicles, heavy-duty vehicles, and heavy-duty engines. This subpart F does not apply for highway motorcycles or for nonroad or stationary engines or equipment.

(b) For purposes of this subpart, the term “you” generally means a clean alternative fuel conversion manufacturer, which may also be called “conversion manufacturer” or “converter”.

The definitions in this section apply to this subpart. All terms that are not defined in this subpart have the meaning given in 40 CFR part 86. All terms that are not defined in this subpart or in 40 CFR part 86 have the meaning given in the Clean Air Act. The definitions follow:

Clean alternative fuel conversion (or “fuel conversion” or “conversion system”) means any alteration of a motor vehicle/engine, its fueling system, or the integration of these systems, that allows the vehicle/engine to operate on a fuel or power source different from the fuel or power source for which the vehicle/engine was originally certified; and that is designed, constructed, and applied consistent with good engineering judgment and in accordance with all applicable regulations. A clean alternative fuel conversion also means the components, design, and instructions to perform this alteration.

Clean alternative fuel conversion manufacturer (or “conversion manufacturer” or “converter”) means any person that manufactures, assembles, sells, imports, or installs a motor vehicle/engine fuel conversion for the purpose of use of a clean alternative fuel.

Conversion model year means the clean alternative fuel conversion manufacturer's annual production period which includes January 1 of such calendar year. A specific model year may not include January 1 from the previous year or the following year. This is based on the expectation that production periods generally run on consistent schedules from year to year. Conversion model years may not circumvent or skip an annual production period. The term conversion model year means the calendar year if the converter does not have a different annual production period.

Date of conversion means the date on which the clean alternative fuel conversion system is fully installed and operable.

Dedicated vehicle/engine means any vehicle/engine engineered and designed to be operated using a single fuel.

Dual-fuel vehicle/engine means any vehicle/engine engineered and designed to be operated on two or more different fuels, but not on a mixture of the fuels.

Heavy-duty engines describes all engines intended for use in heavy-duty vehicles, covered under the applicability of 40 CFR part 86, subpart A.

Light-duty and heavy-duty chassis certified vehicles describes all light-duty vehicles, light-duty trucks, medium duty passenger vehicles, and heavy-duty complete and incomplete vehicles covered under the applicability of 40 CFR part 86, subpart S.

Mixed-fuel vehicle/engine means any vehicle/engine engineered and designed to be operated on the original fuel(s), alternative fuel(s), or a mixture of two or more fuels that are combusted together. Mixed-fuel vehicles/engines include flexible-fuel vehicles/engines as defined in 40 CFR part 86 subpart S.

Original equipment manufacturer (OEM) means the original manufacturer of the new vehicle/engine or relating to the vehicle/engine in its original certified configuration.

Original model year means the model year in which a vehicle/engine was originally certified by the original equipment manufacturer, as noted on the certificate and on the emission control information label.

We (us, our) means the Administrator of the Environmental Protection Agency or any authorized representative.

Link to an amendment published at 89 FR 28144, Apr. 18, 2024.

(a) You are exempted from the tampering prohibition in Clean Air Act section 203(a)(3) (42 U.S.C. 7522)(a)(3) (“tampering”) if you satisfy all the provisions of this subpart.

(b) The tampering exemption provisions described in this subpart are differentiated based on the age of the vehicle/engine at the point of conversion as follows:

(1) “New and relatively new” refers to a vehicle/engine where the date of conversion is in a calendar year that is not more than one year after the original model year. See § 85.510 for provisions that apply specifically to new and relatively new vehicles/engines.

(2) “Intermediate age” refers to a vehicle/engine that has not exceeded the useful life (in years, miles, or hours of operation) applicable to the vehicle/engine as originally certified, excluding new and relatively new vehicles/engines. See § 85.515 for provisions that apply specifically to intermediate-age vehicles/engines.

(3) “Outside useful life” refers to any vehicle/engine that has exceeded the useful life (in years, miles, or hours of operation) applicable to the vehicle/engine as originally certified. See § 85.520 for provisions that apply specifically to outside useful life vehicles/engines.

(c) If the converted vehicle/engine is a dual-fuel or mixed-fuel vehicle/engine, you must submit test data using each type of fuel, except that if you wish to certify to the same standards as the OEM vehicle/engine, you may omit testing for the fuel originally used to certify the vehicle/engine if you comply with § 85.510(b)(10)(ii), (iii), and (iv), § 85.515(b)(10)(iii)(B), (C), and (D), or § 85.520(b)(6)(iii)(B), (C), and (D), as applicable.

(d) This subpart specifies certain reporting requirements. We may ask you to give us more information than we specify in this subpart to determine whether your vehicles/engines conform to the requirements of this subpart. We may ask you to give us less information or do less testing than we specify in this subpart.

(e) EPA may require converters to submit vehicles/engines for EPA testing under any of the three age based programs. Under § 85.510 or § 85.515, if a vehicle/engine is selected for confirmatory testing as part of the demonstration and notification process, the vehicle/engines must satisfy the applicable intermediate and full useful life standards using the appropriate deterioration factors to qualify for an exemption from the tampering prohibition. If an outside useful life vehicle/engine is selected for testing, the vehicle/engine must demonstrate that emissions are maintained or improved upon after conversion to qualify for an exemption from the tampering prohibition.

(f) If you have previously used small volume conversion manufacturer or qualified small volume test group/engine family procedures and you may exceed the volume thresholds using the sum described in § 85.535(f) to determine small volume status in 40 CFR 86.1838-01, 40 CFR 86.098-14, and 40 CFR 86.096-24(e)(2) as appropriate, you must satisfy the requirements for conversion manufacturers who do not qualify for small volume exemptions or your exemption from tampering is no longer valid.

(g) An exemption from the prohibition on tampering applies to previously issued alternative fuel conversion certificates of conformity for the applicable conversion test group/engine family and/or evaporative/refueling family, as long as the conditions under which the certificate was issued remain unchanged, such as small volume manufacturer or qualified small volume test group/engine family status. Your exemption from tampering is valid only if the conversion is installed on the OEM test groups/engine families and/or evaporative emissions/refueling families listed on the certificate.

(h) The applicable useful life of a clean alternative fuel converted vehicle/engine shall end at the same time the OEM vehicle's/engine's original useful life ends.

Link to an amendment published at 89 FR 28144, Apr. 18, 2024.

(a) You are exempted from the tampering prohibition with respect to new and relatively new vehicles/engines if you certify the conversion system to the emission standards specified in § 85.525 as described in paragraph (b) in this section; you meet the labeling and packaging requirements in § 85.530 before you sell, import or otherwise facilitate the use of a clean alternative fuel conversion system; and you meet the liability, recordkeeping, and end of year reporting requirements in § 85.535.

(b) Certification under this section must be based on the certification procedures such as those specified in 40 CFR part 86, subparts A, B, and S and 40 CFR part 1065, as applicable, subject to the following exceptions and special provisions:

(1) Test groups and evaporative/refueling families for light-duty and heavy-duty chassis certified vehicles.

(i) Small volume conversion manufacturers and qualified small volume test groups.

(A) If criteria for small volume manufacturer or qualified small volume test groups are met as defined in 40 CFR 86.1838-01, you may combine light-duty vehicles or heavy-duty vehicles which can be chassis certified under 40 CFR part 86, subpart S using good engineering judgment into conversion test groups if the following criteria are satisfied instead of those specified in 40 CFR 86.1827-01.

(1) Same OEM and OEM model year.

(2) Same OBD group.

(3) Same vehicle classification (e.g. light-duty vehicle, heavy-duty vehicle).

(4) Engine displacement is within 15% of largest displacement or 50 CID, whichever is larger.

(5) Same number of cylinders or combustion chambers.

(6) Same arrangement of cylinders or combustion chambers (e.g. in-line, v-shaped).

(7) Same combustion cycle (e.g., two stroke, four stroke, Otto-cycle, diesel-cycle).

(8) Same engine type (e.g. piston, rotary, turbine, air cooled vs. water cooled).

(9) Same OEM fuel type (except otherwise similar gasoline and E85 flexible-fuel vehicles may be combined into dedicated alternative fuel vehicles).

(10) Same fuel metering system (e.g. throttle body injection vs. port injection).

(11) Same catalyst construction (e.g. metal vs. ceramic substrate).

(12) All converted vehicles are subject to the most stringent emission standards used in certifying the OEM test groups within the conversion test group.

(B) EPA-established scaled assigned deterioration factors for both exhaust and evaporative emissions may be used for vehicles with over 10,000 miles if the criteria for small volume manufacturer or qualified small volume test groups are met as defined in 40 CFR 86.1838-01. This deterioration factor will be adjusted according to vehicle or engine miles of operation. The deterioration factor is intended to predict the vehicle's emission levels at the end of the useful life. EPA may adjust these scaled assigned deterioration factors if we find the rate of deterioration non-constant or if the rate differs by fuel type.

(C) As part of the conversion system description provided in the application for certification, conversion manufacturers using EPA assigned deterioration factors must present detailed information to confirm the durability of all relevant new and existing components and to explain why the conversion system will not harm the emission control system or degrade the emissions.

(ii) Conversion evaporative/refueling families are identical to the OEM evaporative/refueling families unless the OEM evaporative emission system is no longer functionally necessary. You must create any new evaporative families according to 40 CFR 86.1821-01.

(2) Engine families and evaporative/refueling families for heavy-duty engines.

(i) Small volume conversion manufacturers and qualified small volume heavy-duty engine families.

(A) If criteria for small volume manufacturer or qualified small volume engine families are met as defined in 40 CFR 86.098-14 and 40 CFR 86.096-24(e)(2) you may combine heavy-duty engines using good engineering judgment into conversion engine families if the following criteria are satisfied instead of those specified in 40 CFR part 86, subpart A.

(1) Same OEM.

(2) Same OBD group after MY 2013.

(3) Same service class (e.g. light heavy-duty diesel engines, medium heavy-duty diesel engines, heavy heavy-duty diesel engines).

(4) Engine displacement is within 15% of largest displacement or 50 CID, whichever is larger.

(5) Same number of cylinders.

(6) Same arrangement of cylinders.

(7) Same combustion cycle.

(8) Same method of air aspiration.

(9) Same fuel type (e.g. diesel/gasoline).

(10) Same fuel metering system (e.g. mechanical direct or electronic direct injection).

(11) Same catalyst/filter construction (e.g. metal vs. ceramic substrate).

(12) All converted engines are subject to the most stringent emission standards. For example, 2005 and 2007 heavy-duty diesel engines may be in the same family if they meet the most stringent (2007) standards.

(13) Same emission control technology (e.g., internal or external EGR).

(B) EPA-established scaled assigned deterioration factors for both exhaust and evaporative emissions may be used for engines with over 10,000 miles if the criteria for small volume manufacturer or qualified small volume engine families are met as defined in 40 CFR 86.098-14 and 40 CFR 86.096-24(e)(2). This deterioration factor will be adjusted according to vehicle or engine miles of operation. The deterioration factor is intended to predict the engine's emission levels at the end of the useful life. EPA may adjust these scaled assigned deterioration factors if we find the rate of deterioration non-constant or if the rate differs by fuel type.

(C) As part of the conversion system description provided in the application for certification, conversion manufacturers using EPA assigned deterioration factors must present detailed information to confirm the durability of all relevant new and existing components and to explain why the conversion system will not harm the emission control system or degrade the emissions.

(ii) Conversion evaporative/refueling families are identical to the OEM evaporative/refueling families unless the OEM evaporative emission system is no longer functionally necessary. You must create any new evaporative families according to 40 CFR 86.096-24(a).

(3) Conversion test groups/engine families for small volume conversion manufacturers and qualified small volume test groups/engine families may include vehicles/engines that are subject to different OEM emission standards; however, all the vehicles/engines certified under this subpart in a single conversion test group/engine family are subject to the most stringent standards that apply for vehicles/engines included in the conversion test group/engine family. For example, if OEM vehicle test groups originally certified to Tier 2, Bin 4 and Bin 5 standards are in the same conversion test group for purposes of fuel conversion, all the vehicles certified in the conversion test group under this subpart are subject to the Tier 2, Bin 4 standards. Conversion manufacturers may choose to certify a conversion test group/engine family to a more stringent standard than the OEM did. The optional, more stringent standard would then apply to all OEM test groups/engine families within the conversion test group/engine family. This paragraph (b)(3) does not apply to conversions to dual-fuel/mixed-fuel vehicles/engines, as provided in paragraph (b)(7) of this section.

(4)-(5) [Reserved]

(6) Durability testing is required unless the criteria for small volume manufacturer or qualified small volume test groups/engine families are met as defined in 40 CFR 86.1838-01, 40 CFR 86.098-14, and 40 CFR 86.096-24(e)(2), as applicable.

(7) Conversion test groups/engine families for conversions to dual-fuel or mixed-fuel vehicles/engines cannot include vehicles/engines subject to different emission standards unless applicable exhaust and OBD demonstrations are also conducted for the original fuel(s) demonstrating compliance with the most stringent standard represented in the test group. However for small volume conversion manufacturers and qualified small volume test groups/engine families the data generated from exhaust emission testing on the new fuel for dual-fuel or mixed-fuel test vehicles/engines may be carried over to vehicles/engines which otherwise meet the test group/engine family criteria and for which the test vehicle/engine data demonstrate compliance with the application vehicle/engine standard. Clean alternative fuel conversion evaporative families for dual-fuel or mixed-fuel vehicles may not include vehicles/engines which were originally certified to different evaporative emissions standards unless evaporative/refueling demonstrations are also conducted for the original fuel(s) demonstrating compliance with the most stringent standard represented in the evaporative/refueling family.

(8) The vehicle/engine selected for testing must qualify as a worst-case vehicle/engine under 40 CFR 86.1828-10 or 40 CFR 86.096-24(b)(2) through (b)(3), as applicable.

(9) OBD requirements. (i) The OBD system must properly detect and identify malfunctions in all monitored emission-related powertrain systems or components including any new monitoring capability necessary to identify potential emission problems associated with the new fuel.

(ii) Conduct all OBD testing necessary to demonstrate compliance with 40 CFR 86.010-18 or 86.1806-05.

(iii) Submit the applicable OBD reporting requirements set forth in 40 CFR part 86, subparts A and S, and submit the following statement of compliance if the OEM vehicles/engines were required to be OBD-equipped:

The test group/engine family converted to an alternative fuel has fully functional OBD systems and therefore meets the OBD requirements specified in 40 CFR part 86 when operating on the alternative fuel.

(10) In lieu of specific certification test data, you may submit the following attestations for the appropriate statements of compliance, if you have sufficient basis to prove the statement is valid.

(i) The test group/engine family converted to an alternative fuel has properly exercised the optional and applicable statements of compliance or waivers in the certification regulations such as those specified in 40 CFR part 86, subparts A, B, and S and 40 CFR part 1065. Attest to each statement or waiver in your application for certification.

(ii) The test group/engine family converted to dual-fuel or mixed-fuel operation retains all the OEM fuel system, engine calibration, and emission control system functionality when operating on the fuel with which the vehicle/engine was originally certified.

(iii) The test group/engine family converted to dual fuel or mixed-fuel operation retains all the functionality of the OEM OBD system (if so equipped) when operating on the fuel with which the vehicle/engine was originally certified.

(iv) The test group/engine family converted to dual-fuel or mixed-fuel operation properly purges hydrocarbon vapor from the evaporative emission canister when the vehicle/engine is operating on the alternative fuel.

(11) Certification fees apply per 40 CFR 1027.

(12) A certificate issued under this section is valid starting with the indicated effective date and expires on December 31 of the conversion model year for which it is issued. You may apply for a certificate of conformity for the next conversion model year using the applicable provisions for carryover certification. Even after the certificate expires, your exemption from the prohibition on tampering remains valid for the applicable conversion test group/engine family and/or evaporative/refueling family, as long as the conditions under which the certificate was issued remain unchanged, such as small volume manufacturer or qualified small volume test group/engine family status. Your exemption from tampering is valid only if the conversion is installed on the OEM test groups/engine families and/or evaporative emissions/refueling families listed on the certificate. For example, if you have received a clean alternative fuel conversion certificate of conformity in conversion model year 2011 for converting a 2010 model year OEM test group/evaporative/refueling family, your exemption from tampering continues to apply for the conversion of the same 2010 model year OEM test group/evaporative/refueling family as long as the conditions under which the certificate was issued remain unchanged, such as small volume manufacturer status.

(13) Conversion systems must be properly installed and adjusted such that the vehicle/engine operates consistent with the principles of good engineering judgment and in accordance with all applicable regulations.

[76 FR 19866, Apr. 8, 2011, as amended at 79 FR 23681, Apr. 28, 2014]

Link to an amendment published at 89 FR 28146, Apr. 18, 2024.

(a) You are exempted from the tampering prohibition with respect to intermediate age vehicles/engines if you properly test, document and notify EPA that the conversion system complies with the emission standards specified in § 85.525 as described in paragraph (b) of this section; you meet the labeling requirements in § 85.530 before you sell, import or otherwise facilitate the use of a clean alternative fuel conversion system; and you meet the liability, recordkeeping, and end of year reporting requirements in § 85.535. You may also meet the requirements under this section by complying with the requirements in § 85.510.

(b) Documenting and notifying EPA under this section includes demonstrating compliance with all the provisions in this section and providing all notification information to EPA. You may notify us as described in this section instead of certifying the clean alternative fuel conversion system. You must demonstrate compliance with all exhaust and evaporative emissions standards by conducting all exhaust and evaporative emissions and durability testing as required for OEM certification subject to the exceptions and special provisions permitted in § 85.510. This paragraph (b) provides additional special provisions applicable to intermediate age vehicles/engines. Paragraph (b) is applicable to all conversion manufacturers unless otherwise specified.

(1) Conversion test groups for light-duty and heavy-duty chassis certified vehicles may be grouped together into an exhaust conversion test group using the criteria described in § 85.510(b)(1)(i)(A), except that the same OBD group is not a criterion. Evaporative/refueling families may be grouped together using the criteria described in § 85.510(b)(1)(ii).

(2) Conversion engine families for heavy-duty engines may be grouped together into an exhaust conversion engine family using the criteria described in § 85.510(b)(2)(i)(A), except that the same OBD group is not a criterion. Evaporative/refueling families may be grouped together using the criteria described in § 85.510(b)(2)(ii).

(3) Conversion test groups/engine families may include vehicles/engines that are subject to different OEM emission standards; however, all vehicles/engines in a single conversion test group/engine family are subject to the most stringent standards that apply for vehicles/engines included in the conversion test group/engine family. For example, if OEM vehicle test groups originally certified to Tier 2, Bin 4 and Bin 5 standards are in the same conversion test group for purposes of fuel conversion, all the vehicles in the conversion test group under this subpart are subject to the Tier 2, Bin 4 standards. This paragraph (b)(3) does not apply to conversions to dual-fuel/mixed-fuel vehicles/engines, as provided in paragraph (b)(7).

(4) EPA-established scaled assigned deterioration factors for both exhaust and evaporative emissions may be used for vehicles/engines with over 10,000 miles if the criteria for small volume manufacturer or qualified small volume test groups/engine families are met as defined in 40 CFR 86.1838-01, 40 CFR 86.098-14, or 40 CFR 86.096-24(e)(2), as appropriate. This deterioration factor will be adjusted according to vehicle/engine miles or hours of operation. The deterioration factor is intended to predict the vehicle/engine's emission level at the end of the useful life. EPA may adjust these scaled assigned deterioration factors if we find the rate of deterioration non-constant or if the rate differs by fuel type.

(5) As part of the conversion system description required by paragraph (b)(10)(i) of this section, small volume conversion manufacturers and qualified small volume test groups/engine families using EPA assigned deterioration factors must present detailed information to confirm the durability of all relevant new and existing components and explain why the conversion system will not harm the emission control system or degrade the emissions.

(6) Durability testing is required unless the criteria for small volume manufacturer or qualified small volume test groups/engine families are met as defined in 40 CFR 86.1838-01, 40 CFR 86.098-14, or 40 CFR 86.096-24(e)(2), as applicable. Durability procedures for large volume conversion manufacturers of intermediate age light-duty and heavy-duty chassis certified vehicles that follow provisions in 40 CFR 86.1820-01 may eliminate precious metal composition and catalyst grouping statistic when creating clean alternative fuel conversion durability groupings.

(7) Conversion test groups/engine families for conversions to dual-fuel or mixed-fuel vehicles/engines may not include vehicles/engines subject to different emissions standards unless applicable exhaust and OBD demonstrations are also conducted for the original fuel(s) demonstrating compliance with the most stringent standard represented in the test group/engine family. However the data generated from testing on the new fuel for dual-fuel or mixed/fuel test vehicles/engines may be carried over to vehicles/engines that otherwise meet the conversion test group/engine family criteria and for which the test vehicle/engine data demonstrate compliance with the applicable vehicle/engine standards. Clean alternative fuel conversion evaporative families for dual-fuel or mixed-fuel vehicles/engines cannot include vehicles/engines that were originally certified to different evaporative emissions standards unless evaporative/refueling demonstrations are also conducted for the original fuel(s) demonstrating compliance with the most stringent standard represented in the evaporative/refueling family.

(8) You must conduct all exhaust and all evaporative and refueling emissions testing with a worst-case vehicle/engine to show that the conversion test group/engine family complies with exhaust and evaporative/refueling emission standards, based on the certification procedures such as those specified in 40 CFR part 86, subparts A, B, and S and 40 CFR part 1065.

(9) OBD requirements. (i) The OBD system must properly detect and identify malfunctions in all monitored emission-related powertrain systems or components including any new monitoring capability necessary to identify potential emission problems associated with the new fuel. These include but are not limited to: Fuel trim lean and rich monitors, catalyst deterioration monitors, engine misfire monitors, oxygen sensor deterioration monitors, EGR system monitors, if applicable, and vapor leak monitors, if applicable. No original OBD system monitor that is still applicable to the vehicle/engine may be aliased, removed, bypassed, or turned-off. No MILs shall be illuminated after the conversion. Readiness flags must be properly set for all monitors that identify any malfunction for all monitored components.

(ii) Subsequent to the vehicle/engine fuel conversion, you must clear all OBD codes and reset all OBD monitors to not-ready status using an OBD scan tool appropriate for the OBD system in the vehicle/engine in question. You must operate the vehicle/engine with the new fuel on representative road operation or chassis dynamometer/engine dynamometer testing cycles to satisfy the monitors' enabling criteria. When all monitors have reset to a ready status, you must submit an OBD scan tool report showing that with the vehicle/engine operating in the key-on/engine-on mode, all supported monitors have reset to a ready status and no emission related “pending” (or potential) or “confirmed” (or MIL-on) diagnostic trouble codes (DTCs) have been set. The MIL must not be commanded “On” or be illuminated. A MIL check must also be conducted in a key-on/engine-off mode to verify that the MIL is functioning properly. You must include the VIN/EIN number of the test vehicle/engine. If necessary, the OEM evaporative emission readiness monitor may remain unset for dedicated gaseous fuel conversion systems.

(iii) In addition to conducting OBD testing described in this paragraph (b)(9), you must submit to EPA the following statement of compliance if the OEM vehicles/engines were required to be OBD-equipped:

The test group/engine family converted to an alternative fuel has fully functional OBD systems and therefore meets the OBD requirements specified in 40 CFR part 86 when operating on the alternative fuel.

(10) You must notify us by electronic submission in a format specified by the Administrator with all required documentation. The following must be submitted:

(i) You must describe how your conversion system qualifies as a clean alternative fuel conversion. You must include emission test results from the required exhaust, evaporative emissions, and OBD testing, applicable exhaust and evaporative emissions standards and deterioration factors. You must also include a description of how the test vehicle/engine selected qualifies as a worst-case vehicle/engine under 40 CFR 86.1828-10 or 40 CFR 86.096-24(b)(2) through (b)(3) as applicable.

(ii) You must describe the group of vehicles/engines (conversion test group/conversion engine family) that are covered by your notification based on the criteria specified in paragraph (b)(1) or (b)(2) of this section.

(iii) In lieu of specific test data, you may submit the following attestations for the appropriate statements of compliance, if you have sufficient basis to prove the statement is valid.

(A) The test group/engine family converted to an alternative fuel has properly exercised the optional and applicable statements of compliance or waivers in the certification regulations such as those specified in 40 CFR part 86, subparts A, B, and S and 40 CFR part 1065. Attest to each statement or waiver in your notification.

(B) The test group/engine family converted to dual-fuel or mixed-fuel operation retains all the OEM fuel system, engine calibration, and emission control system functionality when operating on the fuel with which the vehicle/engine was originally certified.

(C) The test group/engine family converted to dual-fuel or mixed-fuel operation retains all the functionality of the OEM OBD system (if the OEM vehicles/engines were required to be OBD equipped) when operating on the fuel for which the vehicle/engine was originally certified.

(D) The test group/engine family converted to dual-fuel or mixed-fuel operation properly purges hydrocarbon vapor from the evaporative emission canister when the vehicle/engine is operating on the alternative fuel.

(iv) Include any other information as the Administrator may deem appropriate to establish that the conversion system is for the purpose of conversion to a clean alternative fuel and meets applicable emission standards.

(11) [Reserved]

(12) Your exemption from the prohibition on tampering remains valid for the applicable conversion test group/engine family and/or evaporative/refueling family, as long as the conditions under which you previously complied remain unchanged, such as small volume manufacturer or qualified small volume test group/engine family status. Your exemption from tampering is valid only if the conversion is installed on the OEM test groups/engine families and/or evaporative emissions/refueling families listed on the notification. For example, if you have complied properly with the provisions in this section in calendar year 2011 for converting a model year 2006 OEM test group/evaporative/refueling family, your exemption from tampering continues to apply for the conversion of the same model year 2006 OEM test group/evaporative/refueling family as long as the conditions under which the notification was submitted remain unchanged.

(13) Conversion systems must be properly installed and adjusted such that the vehicle/engine operates consistent with the principles of good engineering judgment and in accordance with all applicable regulations.

[76 FR 19866, Apr. 8, 2011, as amended at 79 FR 23681, Apr. 28, 2014]

Link to an amendment published at 89 FR 28148, Apr. 18, 2024.

(a) You are exempted from the tampering prohibition with respect to outside useful life vehicles/engines if you properly document and notify EPA that the conversion system satisfies all the provisions in this section; you meet the labeling requirements in § 85.530 before you sell, import or otherwise facilitate the use of a clean alternative fuel conversion system; and you meet the applicable requirements in § 85.535. You may also meet the requirements under this section by complying with the provisions in § 85.515.

(b) Documenting and notifying EPA under this section includes the following provisions:

(1) You must notify us as described in this section.

(2) Conversion test groups, evaporative/refueling families, and conversion engine families may be the same as those allowed for the intermediate age vehicle/engine program in § 85.515(b)(1) and (2).

(3) You must use good engineering judgment to specify, use, and assemble fuel system components and other hardware and software that are properly designed and matched for the vehicles/engines in which they will be installed. Good engineering judgment also dictates that any testing or data used to satisfy demonstration requirements be generated at a quality laboratory that follows good laboratory practices and that is capable of performing official EPA emission tests.

(4) OBD requirements. (i) The OBD system must properly detect and identify malfunctions in all monitored emission-related powertrain systems or components including any new monitoring capability necessary to identify potential emission problems associated with the new fuel. These include but are not limited to: Fuel trim lean and rich monitors, catalyst deterioration monitors, engine misfire monitors, oxygen sensor deterioration monitors, EGR system monitors, if applicable, and vapor leak monitors, if applicable. No original OBD system monitor that is still applicable to the vehicle/engine may be aliased, removed, bypassed, or turned-off. No MILs shall be illuminated after the conversion. Readiness flags must be properly set for all monitors that identify any malfunction for all monitored components.

(ii) Subsequent to the vehicle/engine fuel conversion, you must clear all OBD codes and reset all OBD monitors to not-ready status using an OBD scan tool appropriate for the OBD system in the vehicle/engine in question. You must operate the vehicle/engine with the new fuel on representative road operation or chassis dynamometer/engine dynamometer testing cycles to satisfy the monitors' enabling criteria. When all monitors have reset to a ready status, you must submit an OBD scan tool report showing that with the vehicle/engine operating in the key-on/engine-on mode, all supported monitors have reset to a ready status and no emission related “pending” (or potential) or “confirmed” (or MIL-on) diagnostic trouble codes (DTCs) have been stored. The MIL must not be commanded “On” or be illuminated. A MIL check must also be conducted in a key-on/engine-off mode to verify that the MIL is functioning properly. You must include the VIN/EIN number of the test vehicle/engine. If necessary, the OEM evaporative emission readiness monitor may remain unset for dedicated gaseous fuel conversion systems.

(iii) In addition to conducting OBD testing described in this paragraph (b)(4), you must submit to EPA the following statement of compliance if the OEM vehicles/engines were required to be OBD-equipped:

The test group/engine family converted to an alternative fuel has fully functional OBD systems and therefore meets the OBD requirements specified in 40 CFR part 86 when operating on the alternative fuel.

(5) Conversion test groups/engine families for conversions to dual-fuel or mixed-fuel vehicles/engines may not include vehicles/engines subject to different emissions standards unless applicable exhaust and OBD demonstrations are also conducted for the original fuel(s) demonstrating compliance with the most stringent standard represented in the test group. However the data generated from testing on the new fuel for dual-fuel or mixed-fuel test vehicles/engines may be carried over to vehicles/engines that otherwise meet the conversion test group/engine family criteria and for which the test vehicle/engine data demonstrate compliance with the applicable vehicle/engine standards. Clean alternative fuel conversion evaporative families for dual-fuel or mixed-fuel vehicles/engines cannot include vehicles/engines that were originally certified to different evaporative emissions standards.

(6) You must notify us by electronic submission in a format specified by the Administrator with all required documentation. The following must be submitted.

(i) You must describe how your conversion system complies with the good engineering judgment criteria in § 85.520(b)(3) and/or other requirements under this subpart or other applicable subparts such that the conversion system qualifies as a clean alternative fuel conversion. The submission must provide a level of technical detail sufficient for EPA to confirm the conversion system's ability to maintain or improve on emission levels in a worst case vehicle/engine. The submission of technical information must include a complete characterization of exhaust and evaporative emissions control strategies, the fuel delivery system, durability, and specifications related to OBD system functionality. You must present detailed information to confirm the durability of all relevant new and existing components and to explain why the conversion system will not harm the emission control system or degrade the emissions. EPA may ask you to supply additional information, including test data, to support the claim that the conversion system does not increase emissions and involves good engineering judgment that is being applied for purposes of conversion to a clean alternative fuel.

(ii) You must describe the group of vehicles/engines (conversion test group/conversion engine family) that is covered by your notification based on the criteria specified in paragraph (b)(2) of this section.

(iii) In lieu of specific test data, you may submit the following attestations for the appropriate statements of compliance, if you have sufficient basis to prove the statement is valid.

(A) The test group/engine family converted to an alternative fuel has properly exercised the optional and applicable statements of compliance or waivers in the certification regulations such as those specified in 40 CFR part 86, subparts A, B, and S and 40 CFR part 1065. Attest to each statement or waiver in your notification.

(B) The test group/engine family converted to dual-fuel or mixed-fuel operation retains all the OEM fuel system, engine calibration, and emission control system functionality when operating on the fuel with which the vehicle/engine was originally certified.

(C) The test group/engine family converted to dual-fuel or mixed-fuel operation retains all the functionality of the OEM OBD system (if the OEM vehicles/engines were required to be OBD equipped) when operating on the fuel with which the vehicle/engine was originally certified.

(D) The test group/engine family converted to dual-fuel or mixed-fuel operation properly purges hydrocarbon vapor from the evaporative emission canister when the vehicle/engine is operating on the alternative fuel.

(E) The test group/engine family converted to an alternative fuel uses fueling systems, evaporative emission control systems, and engine powertrain components that are compatible with the alternative fuel and designed with the principles of good engineering judgment.

(iv) You must include any other information as the Administrator may deem appropriate, which may include test data, to establish the conversion system is for the purpose of conversion to a clean alternative fuel.

(7) Conversion systems must be properly installed and adjusted such that the vehicle/engine operates consistent with the principles of good engineering judgment and in accordance with all applicable regulations.

(8) EPA may ask for any documentation and/or ask you to conduct emission testing to demonstrate the conversion is for the purpose of a clean alternative fuel.

[76 FR 19866, Apr. 8, 2011, as amended at 79 FR 23681, Apr. 28, 2014]

Link to an amendment published at 89 FR 28149, Apr. 18, 2024.

Prior to April 8, 2011, the following emission standards applied for conversions of vehicles/engines with an original model year of 1992 or earlier:

(a) Exhaust hydrocarbons. Light-duty vehicles must meet the Tier 0 hydrocarbon standard specified in 40 CFR 86.094-8. Light-duty trucks must meet the Tier 0 hydrocarbon standard specified in 40 CFR 86.094-9. Otto-cycle heavy-duty engines must meet the hydrocarbon standard specified in 40 CFR 86.096-10. Diesel heavy-duty engines must meet the hydrocarbon standard in 40 CFR 86.096-11.

(b) CO, NOX and particulate matter. Vehicles/engines must meet the CO, NOX, and particulate matter emission standards that applied for the vehicle's/engine's original model year. If the engine was certified with a Family Emission Limit, as noted on the emission control information label, the modified engine may not exceed this Family Emission Limit.

(c) Evaporative hydrocarbons. Vehicles/engines must meet the evaporative hydrocarbon emission standards that applied for the vehicle's/engine's original model year.

Link to an amendment published at 89 FR 28149, Apr. 18, 2024.

To qualify for an exemption from the tampering prohibition, vehicles/engines that have been converted to operate on a different fuel must meet emission standards and related requirements as described in this section. The modified vehicle/engine must meet the requirements that applied for the OEM vehicle/engine, or the most stringent OEM vehicle/engine standards in any allowable grouping. Fleet average standards do not apply unless clean alternative fuel conversions are specifically listed as subject to the standards.

(a) If the vehicle/engine was certified with a Family Emission Limit for NOX, NOX+HC, NOX+NMOG, or particulate matter, as noted on the vehicle/engine emission control information label, the modified vehicle/engine may not exceed this Family Emission Limit.

(b) Compliance with greenhouse gas emission standards is demonstrated as follows:

(1) Subject to the following exceptions and special provisions, compliance with light-duty vehicle greenhouse gas emission standards is demonstrated by complying with the N2O and CH4 standards and provisions set forth in 40 CFR 86.1818-12(f)(1) and the in-use CO2 exhaust emission standard set forth in 40 CFR 86.1818-12(d) as determined by the OEM for the subconfiguration that is identical to the fuel conversion emission data vehicle (EDV):

(i) If the OEM complied with the light-duty greenhouse gas standards using the fleet averaging option for N2O and CH4, as allowed under 40 CFR 86.1818-12(f)(2), the calculations of the carbon-related exhaust emissions require the input of grams/mile values for N2O and CH4, and you are not required to demonstrate compliance with the standalone CH4 and N2O standards.

(ii) If the OEM complied with alternate standards for N2O and/or CH4, as allowed under 40 CFR 86.1818-12(f)(3), you may demonstrate compliance with the same alternate standards.

(iii) If the OEM complied with the nitrous oxide (N2O) and methane (CH4) standards and provisions set forth in 40 CFR 86.1818-12(f)(1) or (3), and the fuel conversion CO2 measured value is lower than the in-use CO2 exhaust emission standard, you also have the option to convert the difference between the in-use CO2 exhaust emission standard and the fuel conversion CO2 measured value into GHG equivalents of CH4 and/or N2O, using 298 g CO2 to represent 1 g N2O and 25 g CO2 to represent 1 g CH4. You may then subtract the applicable converted values from the fuel conversion measured values of CH4 and/or N2O to demonstrate compliance with the CH4 and/or N2O standards.

(iv) Optionally, compliance with greenhouse gas emission requirements may be demonstrated by comparing emissions from the vehicle prior to the fuel conversion to the emissions after the fuel conversion. This comparison must be based on FTP test results from the emission data vehicle (EDV) representing the pre-conversion test group. The sum of CO2, CH4, and N2O shall be calculated for pre- and post-conversion FTP test results, where CH4 and N2O are weighted by their global warming potentials of 25 and 298, respectively. The post-conversion sum of these emissions must be lower than the pre-conversion conversion greenhouse gas emission results. CO2 emissions are calculated as specified in 40 CFR 600.113-12. If statements of compliance are applicable and accepted in lieu of measuring N2O, as permitted by EPA regulation, the comparison of the greenhouse gas results also need not measure or include N2O in the before and after emission comparisons.

(2) Compliance with heavy-duty engine greenhouse gas emission standards is demonstrated by complying with the CO2, N2O, and CH4 standards (or FELs, as applicable) and provisions set forth in 40 CFR 1036.108 for the engine family that is represented by the fuel conversion emission data engine (EDE). The following additional provisions apply:

(i) If the fuel conversion CO2 measured value is lower than the CO2 standard (or FEL, as applicable), you have the option to convert the difference between the CO2 standard (or FEL, as applicable) and the fuel conversion CO2 measured value into GHG equivalents of CH4 and/or N2O, using 298 g/hp-hr CO2 to represent 1 g/hp-hr N2O. Similarly, you may use 34 g/hp-hr CO2 to represent 1 g/hp-hr CH4 for model year 2021 and later engines, and you may use 25 g/hp-hr CO2 to represent 1 g/hp-hr CH4 for earlier engines. You may then subtract the applicable converted values from the fuel conversion measured values of CH4 and/or N2O to demonstrate compliance with the CH4 and/or N2O standards (or FEL, as applicable).

(ii) Small volume conversion manufacturers may demonstrate compliance with N2O standards based on an engineering analysis.

(iii) For conversions of engines installed in vocational vehicles subject to Phase 2 standards under 40 CFR 1037.105 or in tractors subject to Phase 2 standards under 40 CFR 1037.106, conversion manufacturers may omit a demonstration related to the vehicle-based standards, as long as they have a reasonable technical basis for believing that the modified vehicle continues to meet those standards.

(3) Subject to the following exceptions and special provisions, compliance with greenhouse gas emission standards for heavy-duty vehicles subject to 40 CFR 86.1819 is demonstrated by complying with the N2O and CH4 standards and provisions set forth in 40 CFR 86.1819 and the in-use CO2 exhaust emission standard set forth in 40 CFR 86.1819-14(b) as determined by the OEM for the subconfiguration that is identical to the fuel conversion emission data vehicle (EDV):

(i) If the OEM complied with alternate standards for N2O and/or CH4, as allowed under 40 CFR 86.1819-14(c) you may demonstrate compliance with the same alternate standards.

(ii) If you are unable to meet either the N2O or CH4 standards and your fuel conversion CO2 measured value is lower than the in-use CO2 exhaust emission standard, you may also convert the difference between the in-use CO2 exhaust emission standard and the fuel conversion CO2 measured value into GHG equivalents of CH4 and/or N2O, using 298 g CO2 to represent 1 g N2O. Similarly, you may use 34 g CO2 to represent 1 g CH4.for model year 2021 and later vehicles, and you may use 25 g CO2 to represent 1 g CH4 for earlier vehicles. You may then subtract the applicable converted values from the fuel conversion measured values of CH4 and/or N2O to demonstrate compliance with the CH4 and/or N2O standards.

(iii) You may alternatively comply with the greenhouse gas emission requirements by comparing emissions from the vehicle before and after the fuel conversion. This comparison must be based on FTP test results from the emission data vehicle (EDV) representing the pre-conversion test group. The sum of CO2, CH4, and N2O shall be calculated for pre- and post-conversion FTP test results, where CH4 and N2O are weighted by their global warming potentials as described in paragraph (b)(3)(ii) of this section. The post-conversion sum of these emissions must be lower than the pre-conversion greenhouse gas emission result. Calculate CO2 emissions as specified in 40 CFR 600.113. If we waive N2O measurement requirements based on a statement of compliance, disregard N2O for all measurements and calculations under this paragraph (b)(3)(iii).

(c) Conversion systems for engines that would have qualified for chassis certification at the time of OEM certification may use those procedures, even if the OEM did not. Conversion manufacturers choosing this option must designate test groups using the appropriate criteria as described in this subpart and meet all vehicle chassis certification requirements set forth in 40 CFR part 86, subpart S.

[81 FR 73971, Oct. 25, 2016]

(a) The following labeling requirements apply for clean alternative fuel conversion manufacturers to qualify for an exemption from the tampering prohibition:

(1) You must make a supplemental emission control information label for each clean alternative fuel conversion system.

(2) On the supplemental label you must identify the OEM vehicles/engines for which you authorize the use of your clean alternative fuel conversion system, consistent with the requirements of this subpart. You may do this by identifying the OEM test group/engine family names and original model year to which your conversion is applicable as described in § 85.510(b)(1) or § 85.510(b)(2), § 85.515(b)(10)(ii), or § 85.520(b)(6)(ii). Your commercial packaging materials must also clearly describe this information.

(3) You must include the following on the supplemental label:

(i) You must state that the vehicle/engine has been equipped with a clean alternative fuel conversion system designed to allow it to operate on a fuel other than the fuel it was originally certified to operate on. Identify the fuel or fuels the vehicle/engine is designed to use and provide a unique conversion test group/conversion engine family name and conversion evaporative/refueling emissions family name.

(ii) You must identify your corporate name, address, and telephone number.

(iii) You must include one of the following statements that describes how you comply under this subpart and any applicable mileage or age restrictions due to how compliance was demonstrated:

(A) “This clean alternative fuel conversion system has been certified to meet EPA emission standards.”

(B) “Testing has shown that this clean alternative fuel conversion system meets EPA emission standards under the intermediate age vehicle/engine program.”

(C) “This conversion system is for the purpose of use of a clean alternative fuel in accordance with EPA regulations and is applicable only to vehicles/engines that are older than 11 years or 120,000 miles.” (Values must be adjusted to reflect OEM useful life; useful life in hours should be added, if applicable).

(iv) State the following: “This conversion was manufactured and installed consistent with the principles of good engineering judgment and all U.S. EPA regulations.”

(4) On the supplemental label, you must identify any original parts that will be removed for the conversion and any associated changes in maintenance specifications.

(5) On the supplemental label, you must include the date of conversion and the mileage of the vehicle/engine at the time of conversion. Include the hours of operation instead of mileage, if applicable.

(b) The supplemental emission control information label shall be placed in a permanent manner adjacent to the vehicle's/engine's original emission control information label if possible. If it is impractical to place the supplemental label adjacent to the original label, it must be placed where it will be seen by a person viewing the original label on a part that is needed for normal operation and does not normally need replacement. If the supplemental label information cannot fit on one label, the information can be logically split among two labels that are both near the original VECI or engine label.

(c) All information provided on clean alternative fuel conversion system packaging must be consistent with the required vehicle/engine labeling information.

(d) Examples of all labeling and warranty information must be provided as part of the application for certification or notification process.

(e) The marketing material and label information for a given conversion system must be consistent with the conversion manufacturer's demonstration/notification to EPA for that system.

Link to an amendment published at 89 FR 28149, Apr. 18, 2024.

(a) Clean alternative fuel conversion manufacturers are liable for in-use performance of their conversion systems as outlined in this part.

(b) We may conduct or require testing on any vehicles/engines as allowed under the Clean Air Act. This may involve confirmatory testing, in-use testing, and/or selective enforcement audits for clean alternative fuel conversion systems. Dual-fuel vehicles/engines may be tested when operating on any of the fuels. Mixed-fuel vehicles/engines may be tested on any fuel blend ratio that is expected to occur during normal operation.

(c) Except for an application for certification, your actions to document compliance and notify us under this subpart are not a request for our approval. We generally do not give any formal approval short of issuing a certificate of conformity. However, if we learn that your actions fall short of full compliance with applicable requirements we may notify you that you have not met applicable requirements or that we need more information to make that determination. The exemption from the tampering prohibition may be void ab initio if the conversion manufacturer has not satisfied all of the applicable provisions of this subpart even if a submission to EPA has been made and the conversion system appears on EPA's publicly available list of compliant systems.

(d) Clean alternative fuel conversion manufacturers must accept in-use liability for warranty, are subject to defect reporting requirements, and may be required to recall any parts or systems for which the failure can be traced to the conversion, regardless of whether installation was proper or improper. The OEM shall remain liable for the performance of any parts or systems which retain their original function following conversion and are unaffected by the conversion.

(e) Clean alternative fuel conversion manufacturers must keep sufficient records for five years from the date of notification or certification, or the date of the last conversion installation, whichever is later, to show that they meet applicable requirements.

(f) Clean alternative fuel conversion manufacturers must submit an end of the year sales report to EPA describing the number of clean alternative fuel conversions by fuel type(s) and vehicle test group/engine family by January 31 of the following year. The number of conversions is the sum of the calendar year intermediate age conversions, outside useful life conversions, and the same conversion model year certified clean alternative fuel conversions. The number of conversions will be added to any other vehicle and engine sales accounted for using 40 CFR 86.1838-01 or 40 CFR 86.098-14 as appropriate to determine small volume manufacturer or qualified small volume test group/engine family status.

(g) Conversion manufacturers who market conversion systems for use on vehicles/engines other than the test group/engine families and evaporative/refueling families covered by the compliance demonstration and notification may be liable for a tampering violation for each vehicle/engine to which conversion system is misapplied.