UNITED STATES ENVIRONMENTAL PROTECTION AGENCY 

NATIONAL VEHICLE AND FUEL EMISSIONS LABORATORY 

2565 PLYMOUTH ROAD 

ANN ARBOR, MICHIGAN 48105-2498 

OFFICEOF 

AIR AND RADIATION 

February 3,2006 CISD-06-02 (LD-AFC) 

Dear Manufacturer: 

SUBJECT: Updated Certification Guidance for Alternative Fuel Converters 

This letter, with attachments, supersedes CCD-04-20 dated October 1,2004. It provides information 

for small volume manufacturers' who convert vehicles and engines to operate on alternative fuels. 

Attachments 1, 1-A, 1-B, 1-C and 2 to this letter are documents which provide direction on how to 

comply with EPA requirements when converting a vehicle to an alternative fuel. For convenience, 

this letter repeats those guidance items in CCD-04-20 which have not been changed and therefore are 

still applicable. 

Attachment 1 - Questions and Answers have been revised as follows: 

The answer to Question 10 has been revised to specify that the EPA assigned DFs issued in 

guidance letter CCD-05-10, dated May 26, 2005 must now be used when determining 

compliance with emission standards using the alternative fuel. Previously, and before 

revised EPA assigned DFs were issued, alternative fuel converters were allowed to use the 

OEM's DFs which were used when the vehicle was certified on the original fuel. 

A new question and answer number 41 was added to clarify that EPA's policy on alternative 

fuels conversions applies to all fuel types, not just LPG and CNG which are the only fuel 

types discussed in the previous guidance letter, CCD-05- 10. Since the issuance of CCD-05- 

10, EPA has received inquiries about certifying alternative fueled vehicles which can be 

designed to operate on ethanol (E-85) or vegetable oil. 

A new question and answer number 42 was added stating that alternative fuel converters 

'In this letter a small volume manufacturer is defined as an individual or company who installs a fuel conversion 

system to a vehicle or engine which has been sold to the ultimate purchaser and placed in service allowing the vehicle or engine 

to operate on a fuel other than the fuel which the vehicle or engine was originally certified to use. This is also consistent with the 

definition of aftermarket conversion installer in 40 CFR 85.502. In this letter and attachments the terms aftermarket 

manufacturer and converter are often used interchangeably. 

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@ Printed on Recycled Paper BQ 
must follow the California procedures for measuring NMOG to determine compliance with 

NMOG standards. EPA will consider use of a multiplier to calculate an equivalent NMOG 

result for vehicles operating on other fuels, for example LPG and CNG, when data of 

sufficient quantity and quality are presented to support use of a multiplier. 

Attachment 1-A provides a new web site address to an EPA guidance letter (CCD-05-03) 

describing EPA policy for the review and approval of on-board refueling vapor control 

systems. 

Attachment 2 - Test Requirements for Alternative Fuels Converters has been revised as follows: 

In the first paragraph of the "General" section EPA has clarified that a test waiver must be 

submitted to EPA before a certificate will be issued. This paragraph also states that any first 

time alternative fuel converter should anticipate that their initial vehicle will be confirmatory 

tested by EPA. 

An item number V. has been added providing detail on how to comply with OBD XI 

requirements as they pertain to aftermarket alternative fuels converters. In particular, 

suggested test methods for proving functionality of the OBD system have been described. 

Questions about this letter and its attachments should be directed to Martin Reineman at 734-214- 

4430, or reineman.martin @epa.gov. 

Sincerelv. 

Merrylin Zaw-Mon, Director 

Certification and Compliance Division 

Office of Transportation and Air Quality 

Attachments (5) 

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Attachment 1 to CISD-06-02 

Chassis Certified Alternative Fuels Conversions 

Questions and Answers 

February, 2006 

The answers to the questions are based on the Standards for Emissions from Natural Gas-Fueled, 

and Liquefied Petroleum Gas-Fueled Motor Vehicles and Motor Vehicle Engines, and 

Certification Procedures for Aftermarket Conversions, 59 FR 48472, September 21, 1994, Final 

Rule; 40 CFR Parts 80, 85, 86, 88, 600; and the Clean Air Act as amended. It also references 

EPA guidance documents and web site locations. In the event that an answer conflicts with an 

EPA regulation, the regulation takes precedence. 

1. Can you outline the Certification process for an aftermarket conversion to an alternative 

fuel? 

Ans. See Attachment 1-A, entitled: ACertification and In-Use Requirements for Small Volume 

Manufacturers of Light Duty Vehicle and Light Duty Truck Alternative Fuel 

Conversions. 

2. Will EPA establish a "micro-sales volume" class as described in the November 27, 2001 

letter from the National Propane Gas Association addressed to Bruce Buckheit of EPA's 

Air Enforcement Division? 

Ans. No. There is enough flexibility in our current small volume regulations (40 CFR Part 86, 

Subpart S) to accommodate aftermarket converters of light duty vehicles and trucks to 

alternative fuels and to meet EPA requirements. There are significant testing and 

reporting efficiencies which EPA has already developed to lessen the burden of 

certification. These include reporting changes, use of more representative deterioration 

factors, flexibility in approving waivers of specific tests, and a reduced fee schedule. 

3. How can I assure that an aftermarket conversion does not constitute tampering? 

Ans. Previously, EPA provided guidance on its enforcement policy regarding the tampering 

provision under Section 203(a)(3) of the Clean Air Act. Under the guidance, aftermarket 

manufacturers and installers could modify or convert a vehicle or engine by conducting a 

chassis or engine dynamometer exhaust test for emissions compliance in order to 

demonstrate that the modification does not adversely affect emissions performance, and 

by maintaining all records related to the modification or conversion. That method, 

known as Option 3 of the Addendum to Memorandum 1A, was an interim option 

intended to provide aftermarket manufacturers and installers adequate time to transition 

toward full certification. Effective April 1, 2002, Option 3 is no longer recognized under 

EPA’s enforcement policy. 

Under EPA’s regulations, it is not tampering if you manufacture, distribute or install an 

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aftermarket conversion system or kit that is certified in accordance with EPA’s 

regulations. In addition, if you manufacture, distribute or install an aftermarket 

conversion system or kit certified under the state of California’s revised procedures for 

1994 and subsequent model years vehicles, EPA, under its enforcement policy, does not 

intend to consider the modification as tampering.2 

As a reminder, suppliers and installers of individual replacement parts that have no 

intention of producing and installing parts for the purpose of a full alternative fuel 

conversion can protect themselves from charges of tampering by having a reasonable 

basis to believe that the replacement part is designed to perform the same function with 

respect to emissions as the original part. A copy of Mobile Source Enforcement 

Memorandum No. 1A, dated June 25, 1974 may be viewed at: 

http://www.epa.gov/Compliance/resources/policies/civil/caa/mobile/tamper-memo1a.pdf 

4. What vehicle group(s) does the Certificate apply to? 

Ans. Certificates apply to the "test group" listed on the Certificate and described in the 

manufacturer's application for certification. A test group is a basic EPA classification 

unit and is defined in 40 CFR 86.1803-1. The test group was previously known as the 

engine family. 

5. What model year standards apply to converted vehicles? 

Ans. The applicable standards are discussed in 40 CFR 85.504. 

Model year (MY) 1993 and newer model year vehicles must meet the standards 

applicable at the time the vehicle was originally certified by EPA. For example, a 1996 

MY vehicle converted to alternative fuel usage in the 2002 calendar year must meet the 

applicable 1996 MY standards. 

MY 1992 and earlier vehicles must meet the Tier 0 standards for hydrocarbon, and the 

CO, NOx, particulate, and evaporative emission standards applicable at the time the 

vehicle was originally certified by EPA. 

2 EPA and California have different requirements. EPA certification will not meet California requirements. 

 For further information see: Addendum to Mobile Source Enforcement Memorandum 1A: Tampering Enforcement 

Policy for Alternative Fuel Aftermarket Conversions, dated September 4, 1997 and subsequent revisions, and 

certification regulations and applicable standards set forth at 40 CFR Parts 85 though 88. 

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An alternative fuel converter may certify vehicles to a more stringent standard when 

operated on the alternative fuel. 

6. Where are EPA light duty vehicle and truck emission standards presented? 

Ans. EPA exhaust and evaporative emission standards for light-duty vehicles and light-duty 

trucks are found in the regulations at 40 CFR 86.1810-01 through 1815-02. Standards for 

heavy duty vehicles up to 14,000 GVW are found in 40 CFR 86.1816-05. Pre-Tier 2 

standards are compiled on EPA's web site at www.epa.gov/otaq/stds-ld.htm 

7. What exhaust and evaporative emission tests must be conducted? 

Ans. See Attachment 2, entitled: "Test Requirements for Alternative Fuels Converters. 

8. What are the record keeping requirements for a fuels converter? 

Ans. Converters should retain all records required to be maintained according to 40 CFR 

86.1862-04 for a period of eight years. 

9. Low mileage emission data vehicles may not be available. Is there a restriction on the 

emission data vehicle mileage for aftermarket conversions, and do the assigned 

deterioration factors (DFs) still apply, regardless of mileage? 

Ans. There are no maximum mileage restrictions on the emission data vehicle. The assigned 

DFs for compliance with intermediate and full useful life would then be applied to the 

higher mileage emission data vehicles. 

Cite: 40 CFR 86.1830-01(c). 

10. The assigned deterioration factors (DFs) for gaseous and clean fuel fleet vehicles 

presented in EPA guidance letter CCD-00-12, dated August 24, 2000 appear to be high. 

Are these the only option for assigned DFs for alternative fuels conversions? 

Ans. Updated DFs are found in CCD-05-10 dated May 26, 2005. Alternative fuel converters 

must use these new assigned DFs for emissions measurements from vehicles using the 

alternative fuel. These apply to dedicated alternative fuel vehicles and dual fuel vehicles 

when operating on the alternative fuel. For dual fueled vehicles, use of the OEM's DFs 

when operating on the fuel used by the OEM at the time the vehicle was originally 

certified is contingent on the alternative fuel converter not modifying the components or 

location of the OEM emission control system or the fuel control system, or increasing the 

weight of the vehicle by more than 500 pounds. Aftermarket converters must make a 

statement that they have not altered the OEM's emission control system, and include this 

statement in their application for certification. Alternatively, converters may develop 

their own deterioration factors based on the durability demonstration requirements in 40 

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CFR Parts 86.1823-01, 86.1824-01, 86.1825-01, and 86.1826-01. 

40 CFR Parts 86.1823-01(a)(3), 86.1824-01(a)(2)(v), 86.1826-01(2)(i), and 86.1851-

01(a) provide the flexibility for small volume test group manufacturers, and large volume 

manufactures, to exercise good engineering judgment in applying an appropriate DF to 

the exhaust and evaporative emission results on the alternative fuel. 

11. What laboratories conduct the EPA tests? 

Ans. A list of laboratories that have the capabilities to conduct some or all of the required 

exhaust and evaporative emission testing is supplied by and periodically updated by 

EPA. EPA does not endorse or approve test laboratories, or vouch for the list's 

completeness. The lab list may be viewed at: www.epa.gov/otaq/consumer/lablist.pdf. 

12. Where are test procedures and small volume manufacturer regulations described? 

Ans. Subpart B of 40 CFR Part 86 describes the test procedures for conducting the relevant 

emission tests. Subpart S of 40 CFR Part 86 describes the provisions for conventional 

small volume manufacturers. The CFR is available on-line at: 

http://www.gpoaccess.gov/cfr/index.html. This regulation (and other EPA regulations) is 

available from the EPA web site at: http://www.epa.gov/otaq/ld-hwy.htm#regs Hard 

copies of 40 CFR Part 86 (two volumes) may be ordered by calling 202-512-1803. 

13. How is fuel economy calculated from gasoline, diesel, CNG, or LPG fueled vehicles? 

Ans. Gasoline fuel economy is calculated based on the equation in 40 CFR 600.113-93(e)(1). 

Diesel fuel economy is calculated based on the equation in 40 CFR 600.113-93(f)(1). 

CNG fuel economy is calculated based on the equation in 40 CFR 600.113-93(h). 

Until EPA publishes an LPG fuel economy equation in regulations, manufacturers may 

use the equation presented in Attachment 1-B. 

14. Where are the EPA guidance letters and Advisory Circular letters located? 

Ans. EPA guidance letters, also called Dear Manufacturer letters, may be viewed on the EPA 

web site at: http://www.epa.gov/otaq/cert/dearmfr/dearmfr.htm EPA Advisory Circular 

letters, which preceded the guidance letters, are also available at the same EPA web site. 

15. How much do emission tests cost? 

Ans. Cost information concerning emission testing conducted by independent facilities must 

be obtained directly from that laboratory. EPA does not charge for confirmatory testing 

if it selects a vehicle to receive such testing. The transportation expense of shipping a 

vehicle to the EPA Ann Arbor facility must be borne by the alternative fuels converter. 

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16. How do I submit data and the application for certification to EPA? 

Ans. The data for alternative fuels converters should be entered in EPA's Certification and 

Fuel Economy Information System (CFEIS) or by using a spreadsheet entry form for 

aftermarket alternative fuels converters. EPA is offering the use of the spreadsheet for 

converters as an alternative. The spreadsheet test data become part of the manufacturer's 

application for certification. Completed applications should be sent electronically in pdf 

format, or by CD in pdf format to: banush.russell@epa.gov. The spreadsheet is available 

upon request at the e-mail address above. Instructions for submitting electronic data to 

EPA are found in guidance letter CCD-01-24. CD applications should be sent to the 

attention of Russell Banush of the Certification and Compliance Division, EPA Office 

Building, 2000 Traverwood Dr., Ann Arbor, MI 48105. 

17. Are there any fuel economy test and reporting requirements such as EPA fuel economy 

labels and Corporate Average Fuel Economy (CAFE) submissions for after-market 

conversions? 

Ans. EPA fuel economy requirements apply to all new vehicles sold in the US. They do not 

apply in the case of aftermarket conversions to alternative fueled vehicles. The intent to 

certify aftermarket conversions systems should be stated in the application for 

certification. 

Cite: 40 CFR Part 600. 

18. What are the required fees for filing an application for Certification? 

Ans. Vehicle conversions are subject to current and future fee schedules. EPA does however, 

offer a reduced fee to manufacturers when: 1) the vehicles are offered for sale in the U.S. 

and 2) the full fee exceeds 1% of the projected aggregate retail value added by the 

conversions. 

See EPA guidance letter CCD-04-14, dated July 2, 2004, which is posted on the EPA 

web site at: www.epa.gov/otaq/cert/dearmfr/dearmfr.htm. Initial fee payment is the 

greater of 1% of the retail value added by the conversions or $750. If the number of 

conversions in a test group exceeds 5 or more, or if the value of a single converted engine 

or vehicle is greater than $75,000, a true-up report with additional fees payment will be 

required at the end of the calendar year. Additional information about these changes is 

posted on the EPA fees web at www.epa.gov/otaq/fees.htm. 

Beginning July 12, 2004, converters who qualify for reduced fee payment will have the 

number of allowable vehicle conversions (as stated in the application for certification) 

printed on the certificate, and will not be allowed to convert more than this number of 

vehicles unless a revised certificate for the additional planned conversions has been 

requested of EPA and additional fees paid. Overstatement of planned conversions may 

be used to avoid this situation. Refunds of fee overpayment may be requested if the 

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conversions do not take place. 

19. When and how do I submit payment? 

Ans. See the guidance letter referenced in the answer to question 18 for information on what 

forms to use and where to submit fee payments. This guidance letter supersedes the 

previous fee payment guidance letter, CD-92-07. The fees filing form should be included 

in the application for certification. 

20. How do converters request waivers from certain EPA testing requirements? 

Ans. 40 CFR Part 86 Subparts B and S have provisions allowing the waiver of certain test 

requirements. None of these waivers releases the manufacturer or converter from the 

responsibility of complying with the emission standards, however. In general, test 

waivers are permitted based on an engineering evaluation that all vehicles will comply. 

Direct any questions on this topic to the attention of Russ Banush, 734-214-4925 or 

Banush.Russell@epa.gov or Martin Reineman, 734-214-4430 or 

Reineman.Martin@epa.gov 

21. What underhood emission labels must be added to the vehicle by the alternative fuel 

converter? 

Ans. The converter must print and affix their label next to the OEM's vehicle emission control 

information (VECI) label. See 40 CFR 85.505. 

22. How do we obtain public information from the OEM's application for certification? 

Ans. Requests for information, including information on which tests were run to comply with 

the applicable exhaust, evaporative, and refueling emissions must be submitted under the 

Freedom of Information Act (FOIA). All FOIA requests must include OEM name, 

model year, and test group. Direct these inquiries to the Ann Arbor Certification and 

Compliance Division FOIA officer, Fred Hart, by e-mail or fax to: 

Hart.Frederick@epa.gov fax: 734-214-4869. CFEIS Summary Sheets contain a 

complete listing of what tests were conducted, emission levels, deterioration factors, and 

the standards. The non-confidential information is available after an OEM has received a 

certificate for the test group in question and the vehicle is in production. The FOIA 

requires EPA to send information within 20 business days from the time EPA receives a 

request for information. 

23. What is the statutory emissions "useful life" for aftermarket conversions to alternative 

fuels? 

Ans. The useful life is linked to the emission standard, and therefore varies with respect to the 

vehicle class, model year, emission category, and pollutant in question. The useful life 

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for aftermarket conversion purposes does not extend beyond the useful life of the original 

vehicle. This is because conversions generally rely, at least in part, on emission control 

equipment already on the original vehicle. Pre-Tier 2 standards are listed at 

www.epa.gov/otaq/stds-ld.htm Tier 2 standards may be viewed at 

www.epa.gov/otaq/tr2home.htm 

24. What emission requirements exist for aftermarket conversions that take place beyond the 

useful life of the original vehicle? 

Ans. The prohibition on tampering continues to apply beyond the useful life of the original 

vehicle. The response to Question 3 discusses ways to assure you are not tampering, and 

that response also applies when the conversion occurs beyond the useful life of the 

original vehicle. 

Therefore, an installer of an aftermarket kit is protected from tampering liability if the 

installer properly installs a certified conversion kit. However, if the vehicle is beyond the 

useful life, there is no further in-use liability that the installer must accept, as in-use 

liability does not extend beyond the useful life of the original vehicle. In addition, if you 

manufacture or install a non certified kit, you remain subject to potential liability for 

tampering even if the conversion occurs beyond the useful life of the original vehicle. 

25. What is the emissions warranty period for aftermarket conversions? 

Ans. The emissions warranty starts at the original production date of the vehicle, not the 

conversion date. For example, a vehicle covered by a 5 year/50,000 mile warranty which 

is then converted at 4 years/40,000 miles has 1 year/10,000 miles remaining on its 

emissions warranty. 

The emissions warranty period for vehicles is defined as a function of model year. Prior 

to the 1995 model year the warranty coverage (from the original production date of the 

vehicle and not the conversion date) is: 

5 years/50,000 miles, whichever occurs first, except for certain specified diesel 

components that are warranted for 5 years/100,000 miles. 

2 years/24,000 miles, whichever occurs first, for repairs necessary to correct 

inspection maintenance (I/M) failures. 

For 1995 and later model years the warranty coverage (from the original production date 

of the vehicle and not the conversion date) is: 

General Emissions Warranty - 2 years/24,000 miles, whichever occurs first, 

which also includes repairs necessary to correct I/M failures. 

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Major Emissions Component Warranty - 8 years/80,000 miles, whichever occurs 

first, which includes the catalytic converter, engine control unit, and on-board 

diagnostic (OBD) computer if it is different from the engine control unit. 

Please note: California’s regulations require additional time or mileage warranty 

requirements for the conversion system manufacturer and/or the system installer. 

26. Who is liable for the emissions warranty when a part or system fails on a converted 

vehicle? 

Ans. The vehicle's original manufacturer remains liable for warranty of any systems which 

retain their original purpose following conversion, except in cases where the failure of 

such a system is determined to be caused by the conversion. If the failure of such a part 

or system could be traced to the conversion, then the liability would lie with the 

conversion certifier. For example, a good indication of where the liability lies in such 

situations would be whether the failure of a part or system is also occurring in 

non-converted configurations of the same vehicle. The conversion system manufacturers 

would be responsible for the emissions warranty for any parts or systems added by the 

conversion. 

27. Are there any in-use test responsibilities for alternative fuels converters? 

Ans. Responsibilities for conducting in-use testing under current EPA regulations are 

described in 40 CFR 86.1845-01. There are no in-use test requirements for small volume 

manufacturers with annual sales of less than 5,000 conversions in a given model year. 

28. Do EPA's defect reporting requirements and voluntary recall provisions apply to 

conversions to alternative fuels? 

Ans. Yes. This process is described in 40 CFR Subpart T, Emission Defect Reporting Process. 

 This Subpart describes emission defect reporting, voluntary emissions recall reporting, 

and follow-up reporting requirements. 

29. Alternative fuels converters have different time lines for certification than the vehicle 

OEMs. Alternative fuels conversions also are conducted after the end of an OEM's 

model year. Can EPA extend the applicable time period of the Certificate? 

Ans. No. The Clean Air Act requires Certificates of Conformity to be issued on a model year 

basis. Therefore, certificates cover an annual production period and must be obtained 

each model year. The certificate will expire after December 31st of the year for which it 

is issued. Data and many sections of the application may be carried over to subsequent 

years if no changes are made, but new fees are required for each certificate. 

30. What are the OBD requirements for alternative fuels converters? 

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Ans. For dual fueled vehicles, the OEM OBD system must remain completely functional when 

operating on the fuel on which the vehicle was originally certified. Operation on 

alternative fuels must not falsely register diagnostic trouble codes or illuminate a 

malfunction indicator light (MIL). Dedicated alternative fueled vehicles and dual fuel 

conversions operating on the alternative fuel must have functional OBD II systems 

beginning with 2005 MY light duty vehicle and trucks. More information on EPA 

approval of OBD II systems for alternative fuel converters may be found under item V. 

on page three of Attachment 2. 

31. How long does it take to get a Certificate from EPA once a completed application has 

been submitted to EPA? 

Ans. A manufacturer should plan for at least 30 days for EPA receipt, review, and approval of 

the application once a complete package is submitted. The application must be in a 

format similar to the example presented in EPA guidance letter VPCD-99-06. The 

application should contain all the information on the Aftermarket Alternative Fuels 

Converters worksheets. 

32. How do we receive the Certificate for an alternative fuels conversion? 

Ans. Certificates will be e-mailed to the alternative fuel converter’s designated e-mail address 

for receiving certificates. 

33. Are there State emission requirements in addition to Federal standards? 

Ans. Yes. The aftermarket conversions must pass any state inspection/maintenance (I/M) test. 

 Current I/M test requirements are summarized on EPA's I/M web site at: 

www.epa.gov/otaq/epg/state.htm See Question 40 for certification requirements specific 

to California. 

34. If my vehicle is selected for confirmatory testing at EPA in Ann Arbor, which tests on 

what fuels will be conducted? 

Ans. The exact tests are a function of the model year of the vehicle. Dedicated alternative 

fueled vehicles will typically receive an FTP emission test without the evaporative 

emission test. Dual fueled vehicles will typically receive the FTP with a 2 day 

evaporative emission test on the alternative fuel. EPA confirmatory tests will be 

conducted with the gaseous fuels in the vehicle fuel tank supplied by the alternative fuel 

converter. For dual fuel vehicles, the FTP exhaust, highway NOx, and evaporative 

emission tests, plus the SFTP if applicable, may be run on the fuel on which the vehicle 

was originally certified. 

The manufacturer is responsible for delivering the vehicle to EPA in a test ready 

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condition. This includes the installation of proper fuel drain fittings for testing dual 

fueled vehicles on gasoline and fittings and connections to load the gasoline evaporative 

emission canister for a dual fueled vehicle. Vehicle starting instructions, procedures for 

draining the gasoline fuel tank, and loading the evaporative emission canister must be 

included. Failure to provide this information may result in significant delays. A small 

sample (approximately one liter) of the alternative fuel should be delivered to EPA if the 

vehicle is confirmatory tested in Ann Arbor. 

35. Are there other EPA needs specific to the conversion of aftermarket alternative fueled 

vehicles which should be included in the application for certification? 

Ans. Given that aftermarket conversions may be performed by individuals or organizations 

other than the holder of the original certificate, EPA requests that the conversion system 

manufacturer include in its application for certification a description of the installation 

procedures and maintenance requirements for the conversion system. 

36. How do heavy duty engine requirements for alternative fuels converters differ from light 

duty vehicle requirements? 

Ans. Many of the issues discussed above also apply to obtaining a Certificate of Conformity 

for alternative fuel conversions of heavy duty engines. However, the workshop on 

February 13, 2002 focused almost exclusively on vehicle certification, and the references 

to Subparts B and S of 40 CFR Part 86, and to the above referenced EPA guidance 

documents, apply to light duty vehicles. 

Vehicles above 8,500 GVW have historically been classified as heavy duty and therefore 

are engine certified. Starting with the 2005 MY, or as late as the 2007 MY depending on 

which of three options an OEM selected, all gasoline fueled vehicles below 14,000 GVW 

must be chassis certified. Some manufacturers may have elected to chassis certify some 

of their test groups below 14,000 GVW before the 2005 MY. All chassis certified 

vehicles are identified by a vehicle emission control label as opposed to an engine 

emission control label. 

All conversions of heavy duty engines undergo a certification process using a PC-based 

data entry system. The EPA contact person for engine conversions to alternative fuels is 

Han Lim. His phone number is: 202-343-9286, and e-mail address is: lim.han@epa.gov 

One frequently asked question concerns the acceptability of chassis test data when a 

heavy duty vehicle or engine is converted to operate on alternative fuels. In general, 

EPA will only accept engine dynamometer data to obtain a certificate of conformity for 

aftermarket conversions of heavy duty vehicles or engines. Engine test data are also an 

accepted means to comply with California's requirements for aftermarket conversions of 

heavy duty vehicles and engines. 

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37. Is there any provision to chassis certify a vehicle which was originally engine certified? 

Ans. This is permissible only if the converter conducts all the tests (including all exhaust and 

evaporative emission tests using gasoline if the vehicle is a dual fuel conversion) the 

OEM would have run for a new vehicle. The converter will have to use EPA assigned 

DFs because the OEM’s engine certified DFs do not apply. Essentially, the converter is 

certifying the vehicle as a new small volume manufacturer. 

38. Will EPA provide an example of its preferred format for the cover page of an Application 

for Certification? 

Ans. Attachment 1-C is an example of an acceptable format for the cover page. 

39. What fuels converters have received EPA Certificates of Conformity and therefore may 

be capable of certifying other light and heavy duty vehicles? 

Ans. See www.epa.gov/otaq/cert.htm to find the link to: Contact List for Fuel Converters 

40. What are the California requirements for aftermarket alternative fuels conversions? 

Ans. California has its own requirements for alternative fuel conversions. For questions 

regarding new model year OEM vehicles converted to alternative fuels, contact Duc 

Nguyen at 626-575-6844, or dnguyen@arb.ca.gov For aftermarket conversions, that is, 

conversion of vehicles which have been sold to the ultimate purchaser and placed in 

service, please contact Rose Castro at 626-575-6848, or rcastro@arb.ca.gov 

41. Which fuel types require converters to obtain certificates of conformity from EPA? 

Ans. EPA vehicle emission regulations are basically fuel neutral, meaning standards must be 

met regardless of fuel type. There are, however, differences in some of the test procedure 

requirements depending on the fuel type. For example, some of the evaporative emission 

requirements may be waived for LPG and CNG because they are closed fueling systems. 

 The test procedures in Attachment 2 were developed at a time when almost all the 

interest in aftermarket fuels conversions was based on converting gasoline vehicles to 

LPG or CNG. Subsequent to publication of EPA's policy on fuels conversions in August 

of 2002 and publication of updated guidance in October 2004, EPA has received inquires 

about converting gasoline fueled vehicles to ethanol (E-85) and converting diesel fueled 

vehicles to vegetable oil. Vehicles converted to operate on E-85 or diesel fuel must pass 

the appropriate standards for the fuel type used by the OEM when the vehicle was 

originally certified. EPA will determine which tests must be conducted and which 

procedures followed for certifying with a specific alternative fuel. 

42. May a 1.04 multiplier be applied to a NMHC measurement in lieu of measuring NMOG 

by speciation? 

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Ans. No. EPA regulations only allow use of the 1.04 multiplier in lieu of measuring NMOG 

emissions for vehicles fueled on gasoline. The 1.04 multiplier was developed based on a 

considerable amount of data showing the correlation between NMHC and the 

corresponding NMOG result. Should similar data be developed for CNG or LPG fueled 

vehicles, EPA will consider the use of a multiplier applied to the NMHC value in lieu of 

measuring NMOG. 

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Attachment 1-A to CISD-06-02 

Certification and In-use Requirements for Small Volume Manufacturers of Light Duty 

Vehicle and Light Duty Truck Alternative Fuels Conversions 

1. Contact EPA to obtain an information package for small volume manufacturers (Russell 

Banush at banush.russell@epa.gov; 734-214-4925). Follow instructions shown at 

www.epa.gov/otaq/cfeis.htm and EPA will assign a unique manufacturer identification 

number and an abbreviated manufacturer name. 

2. Request from EPA the non-confidential sections of the Application for Certification, Part 

1, for the manufacturer, model year, and exhaust and evaporative emission test groups 

through the Freedom of Information Act process (see answer to Question 22). 

Alternatively, this information may be obtained from other sources, such as working with 

the OEM vehicle manufacturer. 

3. Contact the OEM directly for any necessary information unavailable from EPA in the 

non-confidential portion of the OEM's application for certification. EPA can provide 

contact numbers for our OEM certification representatives but has no control over how 

they will assist in providing information. 

4. Prepare all the required information under the requirements of 40 CFR Part 86 Subpart S 

as it pertains to vehicle conversions to alternative fuels. 

5. Submit fee payment and fee filing form to the U.S. Treasury, reference EPA guidance 

letter CCD-04-14 and www.epa.gov/otaq/fees.htm. 

6. Perform all required emission tests. 

7. Request on-board refueling vapor recovery (ORVR) approval from EPA if alterations to 

the OEM ORVR system have been made. See EPA guidance letter CCD-02-22, ORVR 

Guidance for Alternative Fuel Systems. If the ORVR system is unchanged, see CCD-05-

03, Attachment A. 

8. Submit a test request sheet to EPA and submit a test vehicle if selected by EPA. 

9. Enter all data in the EPA data base - CFEIS or the optional spreadsheet. 

10. Submit the completed Part 1 Application to EPA electronically. 

11. Get an OBD II approval letter from the California Air Resource Board (CARB) for 

California vehicles or from EPA if the vehicles will not be sold in California. 

12. Obtain an EPA Certificate for Conformity for the vehicle test group. 

13. Build/modify the vehicles. Install a new VECI (Vehicle Emissions Compliance 

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Information) label. 

13. Submit running changes to EPA during the production period as they occur. 

14. Submit final Part 1/Part 2 application to EPA at the completion of the model year. 

15. Submit defect reports and voluntary emission related recall reports to EPA during the 

"useful life" of the vehicle as they occur. 

16. Provide service and consumer support in response to defect reports and running changes 

through technical service bulletins and recall notifications. 

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Attachment 1-B to CISD-06-02 

LPG Fuel Economy Equation 

The following fuel economy equation will be used by EPA to calculate fuel economy for vehicles 

tested on Liquefied Petroleum Gas (LPG) until an equation is added by EPA regulations: 

MPGequiv = [CWFfuel x SGfuel x 3781.8] / [(CWFHC x HC) + (.429 x CO) + (.273 x CO2)] 

Where: 

MPGequiv = Miles per equivalent gallon of liquefied petroleum gas 

SGfuel = Specific gravity of the fuel 

CWFfuel = Carbon weight fraction of the fuel 

CWFHC = Carbon weight fraction of hydrocarbons in the exhaust gas, which 

is assumed to be equivalent to CWFfuel 

HC = Hydrocarbons in grams per mile 

CO = Carbon monoxide in grams per mile 

CO2 = Carbon dioxide in grams per mile 

3781.8 = Grams of H2O per gallon conversion factor 

MPGequiv-gasoline = 1.377 x MPGequiv 

Where: 

1.377 = 1 gallon LPG /0 .726 gallons gasoline, ref. 49 CFR Part 538.8 

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Attachment 1-C to CISD-06-02 

Cover Page Example 

Application for Certification 

Model Year 200X 

Vehicle Type: Light Duty Vehicle (Truck) 

Fuel Type: Dual Fuel (Gasoline/CNG) 

Emission Standards: 

Gasoline: Tier 2 Bin X 

CNG: Clean Fuel Vehicle 

Carlines: (See OEM’s Certificate) 

Converter Test Group Name

Converter Evaporative Family Name

OEM Test Group, Evaporative Family 

Number of vehicles to be converted 

Converter Name, Manufacturer Code 

Address 

Phone/E-mail 

Contact Person Name/Title 

Date

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Attachment 2 to CISD-06-02 

Test Requirements for Alternative Fuels Converters 

January, 2006 

The test requirements for alternative fueled vehicles are contained in 40 CFR Part 86 and 600. 

This document provides guidance, but does not supersede the regulations. In an instance where 

the guidance conflicts with a regulation, the regulation takes precedence. 

General: For all MYs, vehicle classes, and standards: 

Manufacturers must include test waivers and compliance statements in the application for 

certification. The test waiver must be submitted to EPA before a certificate will be issued for any 

test group. EPA will decide whether a confirmatory test at its Ann Arbor, Michigan laboratory 

will be conducted and advise the manufacturer of the test date. (Note: Any first time converter 

will have to submit their test vehicle to EPA for confirmatory testing. After successful 

confirmatory testing for first time manufacturers, EPA will randomly select subsequent test 

vehicles for confirmatory testing.) Conditional certificates may be issued prior to the actual test 

at Ann Arbor. 

Alternative fuel conversions have unique requirements for refueling connections and/or fuel fill 

disconnection. See 40 CFR 86.1810-10(k)(3). In the September 21,1994 final rule EPA 

established standards of 1.2 g HC at nozzle disconnect for refueling CNG vehicles, and a design 

specification of 2.0 cc dead volume space for LPG vehicle refueling nozzles (59 FR 48472 at 

48476). 

CAFE requirements, fuel economy labeling requirements, and gas guzzler penalties do not apply 

to aftermarket alternative fuel conversions. CAFE requirements, fuel economy labeling, and 

possible gas guzzler penalties apply to new alternative fuel vehicles when operated on gasoline 

or diesel fuel. 

I. For LDVs and LDTs meeting Tier 0 or Tier 1 stds: 

A Dedicated LPG or CNG: 

1) Evaporative tests may be waived if a closed fuel system is used provided assembly 

procedures and durability data assure there are no leaks and no deterioration. See CFR 

600.307-95 and requirements in item 2) below. 

2) Refueling test may be waived provided: 

CNG vehicles meet ANSI/AGA NGV1-1994 standards. See 40 CFR 86.1810-

01(k)(3). 

LPG vehicles meet outage valve testing requirements of 40 CFR 86.1810-01(n). 

Manufacturers provide a statement in the application for certification that based 

on development test or engineering data, vehicles will meet the applicable 

certification standard. 

3) Particulate measurement may be waived. See 40 CFR 86.094-23(c)(1). 

4) LDT idle CO test may be waived. See 40 CFR 86.1829-01(b)(5). 

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5) OBD II required for alternative fuels operation starting with conversion of 2005 MY 

vehicles (not the 2005 certificate MY). See 40 CFR 86.1806-01(i). 

6) Cold CO test not required. See 40 CFR 86.201(a) 

7) SFTP not required. See 40 CFR 86.1810-01(h)(i)(4) 

8) FTP intermediate and full useful life standards apply. 

B Dual fueled gasoline/LPG or gasoline/CNG: 

1) If, based on good engineering judgment, the manufacturer does not significantly 

modify the gasoline emission control system or the gasoline fuel control system, and does 

not increase the test weight by more than 500 pounds, gasoline exhaust and evaporative 

emission testing is not required. In general, allowable control system modifications 

which require exhaust and evaporative emission testing on gasoline include any changes 

which increase emissions. See EPA Advisory Circular 64. 

2) If the gasoline fuel supply system or the gasoline refueling or vapor control system is 

significantly modified, conduct all gasoline exhaust tests (includes SFTP, if applicable, 

and cold CO), 2 day and 3 day evaporative emission tests with gasoline, and spit back 

test with gasoline, if applicable, or ORVR tests with gasoline, if applicable. 

3) When testing the vehicle with the alternative fuel system, conduct the 3 day FTP, 

refueling disconnect test, and the refueling loss test if applicable. The running loss test is 

not required for gaseous fueled vehicles. 

Because EPA regulations for alternative fuels allow the use of testing waivers, on a caseby-case basis converters may obtain waivers for evaporative emission testing. To obtain 

a waiver from evaporative emission tests, the alternative fuel converter must provide a 

statement in the application for certification that a closed fuel system has been installed 

in accordance with current American National Standards Institute/American Gas 

Association (ANSI/AGA) and National Fire Protection Association standard 58 (NAPA 

58) requirements, and that the alternative fuel system is leak free and will not show 

emissions deterioration for the useful life of the vehicle when the system is properly 

maintained. In addition, the converter must provide data which demonstrate that dual 

fuel vehicles when operated on the alternative fuel will purge the canister in a manner 

similar to that when operated on gasoline. Alternative fuel converters who have EPA 

approval for evaporative emission test waivers are still responsible for meeting all EPA 

evaporative and refueling emission requirements, and passing any confirmatory 

evaporative emission and refueling testing which EPA chooses to conduct. 

4) Items 2 - 8 under I A above. 

II. For vehicles certified to an NLEV or CFV standard: 

A Dedicated LPG or CNG 

1) NMOG and HCHO required on FTP. 

2) HFET required for highway NOx. 

3) Evaporative emission tests may be waived if a closed alternative fuel system is used. 

See restrictions under I A 1 and 2, above. 

4) Particulate measurement applies to diesels only. 

5) Items 2 - 8 under I A, above. 

B Dual fueled gasoline/LPG or gasoline/CNG 

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1) NMOG and HCHO required on FTP with alt fuel. 

2) HFET with alt fuel required for highway NOx. 

3) Items 1 - 4 under I B, above. 

III. For vehicles certified under Tier 2 standards: 

1) Interim non-Tier 2 standards apply to small volume manufacturers beginning in 2004 

MY. 

2) Tier 2 standards apply to small volume manufacturers beginning in 2007 MY for 

LDV/LLDT vehicles, and for HLDT/MDPVs beginning in 2009 MY. See 65 FR6698, 

Feb 10, 2000. 

3) Items A and B under II, above, as applicable. 

IV. For new heavy-duty vehicle chassis dynamometer standards: 

1) Applies to manufacturers which chassis certify heavy-duty vehicles. See FR Vol. 65, 

No.195, Oct 6, 2000, and FR Vol. 66, No. 12, Jan 18, 2001. 

2) Items A and B under II, above, as applicable. 

V. OBD II requirements for MY 2005 and newer vehicles (< 8500 GVW): 

Beginning with MY 2005 light-duty vehicles and light-duty trucks (MY 2007 for 

complete heavy-duty vehicles between 8,500 and 14,000 pounds GVW) all conversions must be 

OBD II compliant when operating on the alternative fuel. No false OBD codes and/or false MIL 

(malfunction indicator light) illumination should occur. For dual fuel vehicles, the OBD II 

system must not be affected by the conversion when operating the vehicle on gasoline. Testing 

for compliance should be conducted by inducing failures to the emission system. EPA may, at 

its discretion, elect to conduct confirmatory testing at its laboratory to ensure that the OBD II 

system is functional. A letter describing the OBD II system and requesting approval of the 

system should be submitted to EPA, in advance of the complete application for certification. In 

cases where the OBD II system may have deficiencies, the letter should identify the deficiencies 

and what steps are being taken to correct them for future certifications. A CARB (California Air 

Resources Board) letter of approval, if applicable, will not require a separate EPA OBD II 

approval. The approval letter issued by EPA or CARB should be incorporated into the 

application before it is submitted to EPA. 

Suggested methods for showing OBD compliance for aftermarket fuel converters include the 

following: 

Misfire - Determine the rate of mis-fire that will illuminate the MIL using an electronic misfire 

generator. Run an FTP at that threshold to determine the level of exhaust emissions. 

Fuel trim - Determine when the MIL is illuminated for lean shift and rich shift fuel trim using an 

electronic fuel trim generator. Run FTPs at those thresholds to determine the level of exhaust 

emissions. 

Catalyst - Using an aged catalyst, measure emissions when the deteriorated catalyst first 

illuminates the MIL. Achieving the proper level of catalyst deterioration will be a stepwise 

process of aging and emission testing. 

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Oxygen Sensor - Determine the level or oxygen sensor deterioration which first illuminates the 

MIL by a stepwise process of sensor aging and emission measurement. 

Exhaust Gas Recirculation (EGR) - Determine the level of EGR deterioration which first 

illuminates the MIL by a stepwise process of restricting EGR flow and emission measurement. 

EPA regulations require that a deteriorated catalyst illuminate the MIL when an increase of 1.5 

times the non-methane hydrocarbon emission standard above the NMHC level is detected using 

a representative 4000 mile catalyst system. Malfunctions due to misfire conditions, fuel trim 

problems, or malfunctions of the oxygen sensor or EGR system must illuminate a MIL when 

increases in NMHC, CO, or NOx of 1.5 times the respective standard are detected. For two trip 

monitors (monitors which must detect malfunctions on two successive "trips"), setting a pending 

code is satisfactory proof that the MIL will be illuminated due to detection of a malfunction. 

Data and proof of compliance with OBD requirements should be attached to the letter for OBD 

approval. Vehicle conversions to dual fuel operation should also provide proof that the OEM 

OBD system designed for operation on the fuel the vehicle was originally certified with has not 

been compromised. 

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