Jump to main content or area navigation.

Contact Us

Heavy Trucks, Buses, and Engines

Engine and Vehicle Confirmatory Testing

Verify Compliance Information System

Verify: EPA's Engine and Vehicle Compliance Information System is now online. Learn more about Verify.

Search for Documents

Search the Document Index System (DIS) database to find:

  • Advisory Circulars
  • Applications for Certification
  • Certificates of Conformity
  • Certificate Summary Information Reports
  • Manufacturer Guidance Letters
  • Verify System Documentation

You will need Adobe Reader to view some of the files on this page. See EPA's PDF page to learn more.

You may need MS Excel reader Exit EPA Disclaimer to review some of the files on this page.

Below are the steps for confirmatory testing for small spark-ignition (SI) and compression-ignition (CI) engines at EPA's National Vehicle and Fuel Emissions Laboratory (NVFEL). Upon receipt of a test order from EPA, please follow the steps below as you prepare to respond.

Tutorial Video on Confirmatory Testing:

Overview of the Confirmatory Testing (WMV) (12 minutes, 55MB, November 2013)

Test Engine

  1. Identify the engine you will send to EPA.
  2. If desired test the engine at your facility prior to shipment.
  3. If you have an EPA test order please refer to the contact person on your test order for additional information.
  4. When requested by EPA ship the engine to:
  5. EPA’s National Vehicle and Fuel Emissions Laboratory
    2565 Plymouth Road
    Ann Arbor, Michigan  48105

Test Data

EPA must receive the initial test setup documents prior to installation of the test engine in the test cell at NVFEL. Test setup documents must be sent to EPA electronically through EPA’s Central Data Exchange (CDX) using the Verify information system. (The CDX is the single point of entry on the Environmental Information Exchange Network (Exchange Network) for data submissions to EPA). Before a company can send electronic files to the Compliance and Innovative Strategies Division the company's manufacturer code must be entered in Verify and accounts for the company's submitters must be created.

  1. Obtain a manufacturer code and/or register that code in Verify.
  2. Establish CDX user accounts for everyone that will be submitting data to EPA.
    (Note: Under the Compliance Module section of the User Information Spreadsheet users who will be submitting confirmatory test files must check Upload Compliance Documents.)

The CDX Upload Instructions for Nonroad Engine Manufacturers (PDF) (10 pp, 1.3MB, EPA420-B-08-010, April 2008) provide information on the steps to be followed for data submittal after the company's CDX account is established and ready for use. The following test setup documents list the information EPA requires to run the tests:

After the submitter’s account is created and the user is logged into CDX, upload the Engine Test Set Up documents by selecting the Verify Upload Documents option. The official EPA test results will be sent to the user's MyCDX inbox.

Top of page

Test Process

  1. Follow all instructions on the test order.
  2. Upon arrival at NVFEL or alternative EPA test site or laboratory, the engine will be added to the queue for testing.
  3. EPA will notify the engine manufacturer approximately two weeks prior to the start of testing.
  4. Manufacturers must inform EPA certification representative or contact listed in the test order if they plan to attend the test setup. The testing procedure is provided in the process flow chart (PDF). (1 pg, 15K)
  5. Manufacturers are not permitted to observe the testing.
  6. Manufacturers will be notified upon completion of a valid confirmatory test and allowed to review the draft emissions test report on the first day of testing.
  7. If the engine should fail the first emission test the manufacturer will be permitted to make mechanical repairs to the engine on the second day.
  8. Any changes made to the engine must be documented and provided in writing or electronically to EPA certification personnel at the time of testing.
  9. The final results will be mailed to the manufacturer and will serve as official test results.

Top of page

This page is maintained by EPA's Office of Transportation and Air Quality (OTAQ).
For more: About Us | Get E-mail Updates | Browse the A to Z Subject Index.

Jump to main content.