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 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.