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  2. Vehicle and Engine Certification

Manufacturer Information, Guidance Letters and Advisory Circulars for Vehicle, Engine, and Equipment Programs

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Search for documents in EPA's Transportation & Air Quality database:
  • Document Index System
On this page:
  • Overview of manufacturer information and guidance letters
  • Find letters by year they were issued
  • How to get notified when new letters are issued
  • Advisory circulars

Overview of Manufacturer Information and Guidance Letters

These letters provide information, guidance, and instructions to the regulated industry on specific compliance topics and issues.

Find Letters by Year They were Issued

The links below will take you to all the letters that were issued for that year.

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How to Get Notified when New Letters are Issued

EPA uses a list server to notify manufacturers when a manufacturer information or guidance letter has been issued.

The list server notice:
  • Goes out to the entire list server distribution list;
  • Uses the subject line to specify to which industry(s) the letter applies; and
  • Provides the website location for viewing and/or downloading the new guidance letter.

Subscribe to List Server

To join the "manufacturer-info" list server, send an email to join-manufacturer-info@lists.epa.gov.

Unsubscribe from List Server

To unsubscribe from the " manufacturer-info" list server, send a blank email message to:
leave-manufacturer-info@lists.epa.gov

Advisory Circulars

Advisory Circulars provide more background information about many issues associated with new vehicle and engine compliance.

  • All advisory circulars

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 January 17, 2025
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