The Division of Motor Vehicles Emissions Program regulates the emissions testing facilities, and inspectors working in the emissions program areas. The program includes diesel testing facilities, fleet facilities, and Envirotest, which performs emissions testing for the state under contract and 1981 and older testing facilities.

Covert (unannounced) and overt (observation & hands on) test audits of facilities and inspectors who do emissions tests for the citizens of the state are conducted on a regular basis. The frequency of these test audits is defined by Colorado law. 

Complaints pertaining to an emissions test, facility, staff, or damage to a vehicle during testing should be reported to the department and/or facility for resolution.  The "Garage Repair Act" is in place to help citizens, who have been charged for repairs, obtain refunds if an investigation determines emissions repairs were not needed, or parts in good working order were replaced.

• Enhanced Area  - The full counties of Boulder, Broomfield, Denver, Douglas, and Jefferson, as well as the partial counties of Adams, Arapahoe, Larimer and Weld.
• Basic Area - El Paso county. The gas vehicle emissions program has ended in this area but the diesel program is still in effect.  
• Effective November 1, 2010, portions of Larimer and Weld counties require testing on gas powered vehicles.