Vehicle and Engine Certification

Lists of EPA-Compliant Alternative Fuel Conversion Systems

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All of these lists are updated periodically. Please check back for updates.

Conversion Systems for New Vehicles or Engines

How to Find Certificates of Conformity

EPA issues a certificate of conformity for all new certified conversions.

To find the certificate of conformity for system conversions to be used on light-duty vehicles or engines (passenger vehicles) and locomotives:
  1. Search the Document Index System (DIS)
  2. From the DIS Home screen:
    1. Select “Certificates of Conformity” as the Compliance Document Type; and
    2. Select “Alternative Fuel Conversions” as the Industry.
To request the certificate of conformity for system conversions to be used on heavy-duty vehicles or engines (commercial trucks and buses):
  1. Send an email to Fakhri Hamady at: hamady.fakhri@epa.gov

How to find raw data

To view raw certification data for conversions systems to be used on light-duty vehicles/engines, go to:
To view a complete list of certified conversion systems to be used on heavy-duty vehicles/engines (in the raw data format):
  1. Go to the following section: 
  2. Download the applicable Excel spreadsheet.
  3. Filter by the conversion fuel or the name of a specific manufacturer.

Certified conversion systems may be applied to new and relatively new, intermediate age, or outside useful life vehicles/engines covered by the conversion certificate.

In order to be included on this list, a conversion system must be issued a certificate of conformity. However, due to processing differences, not all conversion systems that have a certificate are included.

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Conversion Systems for Intermediate-Age Vehicles or Engines

Conversion systems on this list may be applied to intermediate age or to outside useful life vehicles/engines covered by the conversion manufacturer's compliance demonstration.

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Conversion Systems for Outside Useful Age Vehicles or Engines 

Conversion systems on this list may only  be applied to vehicles/engines that have exceeded their regulatory useful life as indicated in the conversion manufacturer's compliance demonstration.

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Vehicle and Engine Certification