Skip to main content
U.S. flag

An official website of the United States government

Here’s how you know

Dot gov

Official websites use .gov
A .gov website belongs to an official government organization in the United States.

HTTPS

Secure .gov websites use HTTPS
A lock (LockA locked padlock) or https:// means you’ve safely connected to the .gov website. Share sensitive information only on official, secure websites.

    • Environmental Topics
    • Air
    • Bed Bugs
    • Cancer
    • Chemicals, Toxics, and Pesticide
    • Emergency Response
    • Environmental Information by Location
    • Health
    • Land, Waste, and Cleanup
    • Lead
    • Mold
    • Radon
    • Research
    • Science Topics
    • Water Topics
    • A-Z Topic Index
    • Laws & Regulations
    • By Business Sector
    • By Topic
    • Compliance
    • Enforcement
    • Laws and Executive Orders
    • Regulations
    • Report a Violation
    • Environmental Violations
    • Fraud, Waste or Abuse
    • About EPA
    • Our Mission and What We Do
    • Headquarters Offices
    • Regional Offices
    • Labs and Research Centers
    • Planning, Budget, and Results
    • Organization Chart
    • EPA History

Breadcrumb

  1. Home
  2. Vehicle and Engine Certification

Lists of EPA-Compliant Alternative Fuel Conversion Systems

Related Topic
  • Vehicle and Engine Alternative Fuel Conversions
On this page:
  • Conversion systems for new vehicles or engines
  • Conversion systems for intermediate-age vehicles or engines
  • Conversion systems for outside useful life vehicles or engines

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

Conversion Systems for New Vehicles or Engines

Help
  • How to find certificates of conformity
  • How to find raw data

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:
  • Annual certification test data for vehicles and engines
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:
    • Engine certification data: Large engines
  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.

  • Certified conversion systems for new vehicles or engines (xlsx) (819.09 KB, February 2025)
    Includes ALL light-duty and heavy-duty chassis certified conversions. Includes ONLY certified heavy-duty conversions where the manufacturer requested to be included on this list.

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.

  • Conversion systems for intermediate-age vehicles or engines (xlsx) (55.82 KB, February 2025)

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.

  • Conversion systems for outside useful life vehicles or engines (xlsx) (635.48 KB, June 2024)

Vehicle and Engine Certification

  • Onroad
  • Nonroad
  • EV-CIS
Contact Us about Vehicle and Engine Certification
Contact Us to ask a question, provide feedback, or report a problem.
Last updated on March 28, 2025
  • Assistance
  • Spanish
  • Arabic
  • Chinese (simplified)
  • Chinese (traditional)
  • French
  • Haitian Creole
  • Korean
  • Portuguese
  • Russian
  • Tagalog
  • Vietnamese
United States Environmental Protection Agency

Discover.

  • Accessibility Statement
  • Budget & Performance
  • Contracting
  • EPA www Web Snapshot
  • Grants
  • No FEAR Act Data
  • Plain Writing
  • Privacy
  • Privacy and Security Notice

Connect.

  • Data
  • Inspector General
  • Jobs
  • Newsroom
  • Regulations.gov
  • Subscribe
  • USA.gov
  • White House

Ask.

  • Contact EPA
  • EPA Disclaimers
  • Hotlines
  • FOIA Requests
  • Frequent Questions
  • Site Feedback

Follow.