Diesel Vehicles

Diesel Emissions Program

Which counties require a passing emissions test to register a vehicle?

  • Boulder
  • Jefferson
  • Broomfield
  • Denver
  • Douglas
  • Portions of Adams
  • Portions of Arapahoe
  • Portions of Larimer
  • Portions of Weld
  • Portions of El Paso

See our map for testing locations and diesel emissions area boundaries. For hours of operation, please contact the diesel testing station. If you are unsure if a diesel test is required in your area, please contact your local county motor vehicle office.


Frequently Asked Questions (FAQs)


Yes. Effective June 1, 2017 all diesel vehicles that do require a passing emission test (Boulder, Jefferson, Broomfield, Denver and Douglas Counties, and portions of Adams, Arapahoe, Larimer, Weld and El Paso counties) are eligible for online renewal.

Diesel emission testing facilities charge up to one-hour of the posted labor rates, so fees will vary. Contact the specific station for fees.

  Map of testing locations and diesel area boundary    

  List of licensed diesel emissions stations