FAQ: Quick Consumer Information

Hours of Operation:

Monday to Friday, 8 a.m. to 5:30 p.m. and Saturdays, 8 a.m. to 1 p.m.
Closed Sundays and state holidays.

PLEASE NOTE: Animals are not allowed in the waiting booths. Please wait with your pets outside of the building. Service animals, specifically trained to aid persons with disabilities, are welcome.Look up a vehicle's recent emissions testing history.

Vehicle Test History

With few exceptions, all gasoline-powered vehicles require emissions inspections once they are over seven years old.  This requirement applies to most vehicles with registered mailing addresses in the seven Denver-metropolitan area and North Front Range counties (Adams, Arapahoe, Boulder, Broomfield, Denver, Douglas, Jefferson, Larimer and Weld).  Please check the registration renewal postcard from the home county to determine if your vehicle is due for an inspection.

NOTE: If your vehicle is registered in a county outside the program area but is driven at least 90 days a year into the program area for employment or school, an emissions inspection is required.

The registration renewal postcard will indicate one of the following:

An emissions inspection is required due by the end of the month of the registration expiration (an additional one-month grace period is allowed).

The vehicle was identified on the road as exceptionally clean by the RapidScreen data collection units and is eligible to skip the next scheduled visit to an Air Care Colorado facility.


Please contact your county Motor Vehicle Office for more specific information.

Most vehicles do not require an inspection until they are eight years old.  Once they have reached age, most 1982-and-newer vehicles are inspected every two years while most 1981-and-older vehicles are inspected annually.  Additionally, an inspection is required when a vehicle that is at least seven years old changes ownership.  A valid Certificate of Emissions Compliance must be supplied by the seller at the time of the sale.

Yes; however, the diesel inspection is a separate program operated by the state of Colorado.  For more information on the diesel inspection program and a map of diesel inspection stations, please visit: 
or here:

Air Care Colorado facilities are open Monday through Friday from 8 a.m. to 5:30 p.m. and Saturday from 8 a.m. to 1 p.m.  All facilities are closed on Sunday and state holidays.

The length of an inspection varies based upon a number of factors, including the type of vehicle. However, most inspections are completed in less than 20 minutes from arrival at the facility.  Air Care Colorado updates wait time information on this website as an added convenience to the motorist. Please check the Locations & Maps page for up-to-date wait times.

An inspection is $25.  The only exception is a reduced fee ($15) for 1981-and-older vehicles.

Air Care Colorado facilities accept cash, checks and credit cards (Visa, MasterCard and Discover).  Please make checks payable to Air Care Colorado.

Note: Vehicle sellers must provide either a new Certificate of Emissions Compliance or an emissions inspection voucher at the time of sale.

There are 18 conveniently-located Air Care Colorado emissions facilities located throughout the Denver-metropolitan area and the North Front Range.  Please check the Visit the Locations & Maps page for locations and directions.

You simply need to present the vehicle for inspection.  No paperwork is required at the time of the inspection.

Depending upon the age and type of vehicle, the following tests are performed:

On-Board Diagnostics (OBD)

OBD is a non-driving test in which the vehicles on-board computer is connected to a computer at the Air Care Colorado facility that accesses various information.  This includes details about the "Check Engine" light, other dashboard indicators and codes that help determine emissions-related problems for quicker repair and improved performance.

I/M 240

The I/M240 is the "treadmill" test most commonly identified with emissions inspections in the Denver-metropolitan area and the North Front Range.  Vehicles are driven on a device known as a dynamometer that simulates a four-minute driving cycle under a variety of conditions (uphill, downhill, acceleration and more) to evaluate emissions.

"Basic" Two-Speed Idle Test

This is the original type of test that evaluates emissions at two different idle speeds. It is used as part of the inspection for 1981-and-older vehicles.

Alternative tests

Sometimes tests may not be performed as part of the overall inspection because the vehicles configuration or onboard computer are preventing communication with the equipment at the Air Care Colorado facility.  Vehicles also may be selected randomly for on-going program studies that are continually used by the State of Colorado for quality assurance purposes to evaluate overall program effectiveness.

Gas Cap Test

A properly functioning gas cap is an essential part of the emissions control system of every vehicle.  Missing or leaking gas caps will cause vehicles to fail the emissions inspection.  A full retest is required if a vehicle fails an initial inspection for a missing or defective gas cap because the gas cap affects the overall emissions control capability.  The vehicle must be inspected completely with the new gas cap in place in order to be properly evaluated.


RapidScreen is an alternative to the inspection at an Air Care Colorado facility first used right here in Colorado!  RapidScreen utilizes data collection units placed roadside that can evaluate emissions as a vehicle drives by.  It is an alternative to the standard inspection and is used to identify vehicles that are operated exceptionally cleanly.  Please visit the RapidScreen page on this website for more information.

Vehicles equipped with readiness monitors are manufactured to allow the OBD system to identify potential emissions-related problems.  Some vehicles have as many as 11 such monitors.  Some of monitors run whenever the vehicle is operating while others run only periodically.  Once a monitor has run through its self-evaluation cycle, it automatically resets.

Vehicles that are inspected using the OBD test can only be inspected if the monitors have been reset to "Ready" to ensure the system has properly performed this self-evaluation cycle.  Specific conditions must be met while driving for the monitors to reset.  Some vehicle manufacturers provide specific driving procedures to reset monitors.  You may also consult with your repair technician.

This form is documentation that a vehicle presented for inspection at an Air Care Colorado facility could not be inspected.  Specific reasons are checked on the form.  Reasons may include missing or inaccessible equipment, a vehicle malfunction or other factors that make it unsafe to inspect the vehicle.  If you receive this form, the identified reason must be addressed and/or repairs performed before it can be inspected.

Vehicles may fail inspections for a variety of reasons.  Some of the more common reasons are:

  • allowable emissions limits were exceeded;
  • the OBD system detected problems;
  • one or more dashboard warning lights remain illuminated during the inspection, indicating that repairs are needed;
  • emissions control equipment and/or the gas cap are either missing or malfunctioning;
  • visible smoke is emitted during the inspection.

Check the Air Care Colorado Brochure "My Vehicle Has Failed Its Emissions Test ... Now What Do I Do?" provided after the inspection for more information.

As of August 10, 2022
Automotive Dealer Emissions Liability Extended
from 3 to 5 days post-purchase

With the passage of the Deter Tampering Motor Vehicle Emissions Control Systems Act (SB22-179), the period during which an auto dealer is liable for a recently purchased gas-powered motor vehicle's compliance with Colorado emissions standards has been extended from three to five business days after purchase.

Beginning August 10, 2022, vehicle buyers must be informed of the extension when the emissions testing coupon is given to the customer to sign. New, updated vehicle emissions testing coupons will be available at the main Air Care Colorado office by August 31, 2022. Air Care Colorado will continue to honor the existing emissions testing coupons during the inventory transition.

Please contact the Division of Motor Vehicles Emissions Team at 303.205.5603 if you have any questions.

If a newly-purchased used vehicle fails its inspection, consumers have five business days (beginning the day after taking possession of the vehicle) to return it to the dealer/seller for repairs or repurchase. A business day is defined as Monday through Saturday with exceptions for state holidays. The dealer/seller is required by state law to either repair, pay a third party to repair, or repurchase the failed vehicle. If a vehicle is purchased from a dealer, the buyer must choose an option within five business days after the vehicle has been returned.

If the failed vehicle is not returned within the initial five-day period, the dealer/seller is relieved of any legal responsibility to repair or repurchase the vehicle.

If your vehicle failed an initial inspection, received documented repairs that cost at least $715, and still failed a re-inspection, you may apply for a waiver from the Colorado Department of Revenue. There are two types of waivers available if a vehicle continues to fail the emissions inspection. For eligibility requirements, please contact the Colorado Department of Revenue at 303-205-5603. Be sure to have the most recent failed emissions inspection report available before calling.

There are several categories of collectors vehicles that have different inspection requirements depending upon the age of the vehicle. Typically, vehicles built before 1976 can be registered as collector vehicles and may not be required to have their emissions inspection. However, this exception must be granted by the state of Colorado and is not assumed. Please contact the Colorado Department of Revenue at 303-205-5603 for more information.

Simply follow the instructions on the vehicle registration renewal postcard provided by the home county.

If you reside outside of the nine-county program area but commute into the area 90 days or more each year for employment or school, an emissions inspection may be required. This applies to:

  • Frequent commuters into the Denver-Boulder and North Front Range areas;
  • Students who keep vehicles locally but whose legal residences are in another part of the state or out of state;
  • Military personnel who are stationed in the program area and keep vehicles locally, but whose legal residence are in another part of the state or out of state;
  • Generally, vehicles registered to motorists residing outside the program area but commuting into the program area 90 days or more each year.

Colorado residents temporarily residing outside of the state may apply for an emissions extension. For complete instructions, please contact the Colorado Department of Revenue at 303-205-5603.

Contact the Colorado Department of Public Health and Environment at 303-692-3211 or email information to cdphe.smokeline@state.co.us.  Please include the suspected vehicle's license plate number and, if possible, whether it's gasoline- or diesel-powered. This hotline is only for reporting smoking vehicles with permanent Colorado license plates and not out-of-state plates or temporary tags.

Still have questions? Air Care Colorado maintains a consumer hotline for more information about emissions inspections. Customer service representatives are available from 8 a.m. to 5 p.m. Monday to Friday. Both English- and Spanish-speaking operators are available. Se habla Espanol. Please call:

303-456-7090 in the Denver-metropolitan area
970-247-8378 in the North Front Range

Recorded information is available on the hotline 24 hours a day. Motorists also may leave a voicemail message during off hours. Calls will be returned during regular business hours.