Emissions testing of gas‑ and diesel‑powered vehicles is required when registering or selling vehicles in Boulder, Broomfield, Denver, Douglas, and Jefferson counties, and in portions of Adams, Arapahoe, Larimer, and Weld counties, as shown in the Air Care Colorado program area maps. Parts of El Paso County also require diesel vehicles to obtain emissions testing prior to sale. Emissions tests for 1982 or newer motor vehicles are valid for 24 months and tests for 1981 or older motor vehicles are valid for 12 months.
Required emissions testing. The table below highlights the vehicles requiring testing in Colorado emissions areas.
Does My Vehicle Need an Emission Test?
Vehicle Type
Emission Test Needed?
Notes
New car (gasoline)
Vehicles purchased from a dealer are exempt from testing for the first seven model years.
1982‑and‑newer gasoline vehicles over seven model years old
Every two years.
1981‑and‑older gasoline vehicles
Selling car/Change of ownership
Responsibility of seller; if a vehicle is purchased with 12 or more months left on original seven‑year exemption, no test is required at the time of sale.
(vehicles registered outside emissions area but driven into area 90 or more days per year for work or school)
Vehicle model year rules apply. Must inform county when no longer commuting.
Every two years for model year 2010 or older.
Collector vehicle model year 1975‑and‑older
Must be registered as a "collector's item."
Collector vehicle model years 1976 to 1985
If vehicle was registered as a collector's item prior to Sept. 1, 2009, and the registration has never lapsed or expired, no test is needed.
Alternative fuel vehicles
Vehicles that run on the following fuel types require emissions testing: ethanol, natural gas, propane, methanol, bio‑diesel, propane/gas, methanol/gas, natural gas/diesel, natural gas/gas, and ethanol gas.
All electric vehicles (with no gas tank or tail pipe emission)
However, if the vehicle is a hybrid, an emissions test is required (see Hybrids).
Light‑duty diesel vehicles 2007 and older
Light‑duty diesel vehicles 2008 and newer
Every two years.
New light‑duty diesel vehicles
New vehicles are exempt from testing for the first four years.
Source: Section 42‑4‑301, et seq., C.R.S.
Exemptions. As noted above, there are several exemptions to emissions requirements. New vehicles are exempt from emissions testing requirements for the first seven model years. In addition, when a newer vehicle is sold with 12 months or more left on the original seven‑year emissions inspection exemption, the vehicle does not require testing at the time of sale. Vehicles that are all‑electric are exempt from emissions testing. New diesel vehicles are exempt for the first four model years. Heavy‑duty diesels (26,000 GVWR or more) model year 2015 and newer are exempt from testing for the first six model years.
Waivers. The state Division of Motor Vehicles can issue waivers for the emissions test requirement in three circumstances:
RapidScreen. RapidScreen is the mobile emissions testing program in Colorado. Instead of testing a vehicle at an emission testing location, owners drive by a mobile testing unit. Vehicles must drive by a testing unit and receive two clean readings at least 60 days prior to a vehicle's registration renewal month. If the vehicle passed inspection, owners will receive notification on their next renewal registration statement. Motor vehicle owners simply pay the emission testing fee during their registration renewal. RapidScreen unit locations can be found here.
Smoking vehicle. Report excessive smoking vehicles to the Smoking Vehicle Hotline at 303‑692‑3211.
For more about emission testing in Colorado, visit: