Does My Vehicle Need an Inspection?

The following gasoline-powered vehicles require emissions inspections:

  • Vehicles that are more than seven (7) model years old, and are:
  • Light-duty gasoline-powered vehicles weighing 8,500 pounds or less.
  • Heavy-duty vehicles weighing more than 8,500 pounds.
  • Vehicles registered to mailing addresses in these areas:
    All of Boulder, Broomfield, Denver, Douglas and Jefferson counties, and parts of Adams, Arapahoe, Larimer and Weld counties.
  • Vehicles registered to mailing addresses outside the Automobile Inspection and Readjustment (AIR) program area but driven at least 90 days a year into the program area for employment or school.

Check the registration renewal postcard, sent in the mail, to determine if a vehicle is due for an inspection. The postcard will indicate one of the following:

Due by the end of the month of the registration expiration.

Vehicle was "clean screened" through the RapidScreen roadside emissions testing program.


Some vehicles don't require an emissions inspection, including:

  • Vehicles that are seven (7) model years old and newer.
  • Vehicles in their "off" year cycle - vehicles require an inspection every other year.
  • All-electric vehicles (hybrid-electric vehicles are inspected after 7 years).
  • Collector plated vehicles (model year 1975 and older).
  • Horseless carriages, street rods, farm vehicles, kit cars and motorcycles.

Contact your county Motor Vehicle Office for more specific information.

How Often Does My Vehicle Need an Inspection?

  • Vehicles seven (7) years and newer do not require inspection.
  • Vehicles eight (8) years and older, back to model year 1982, require an inspection every two years.
  • Vehicles model year 1981 and older are inspected every year.
  • An inspection is required when a vehicle that is seven (7) years or older changes ownership. Change of ownership requires a new passing emissions certificate supplied by the seller at the time of the sale. This requirement doesn’t apply to vehicles that have 365 days remaining on the seven (7) model year exemption.
  • Inspection required for registration renewal when indicated on your registration renewal card.

Do Diesel-Powered Vehicles Require Inspections?

Yes, but Air Care Colorado stations DO NOT inspect diesel-powered vehicles. Diesel vehicles are inspected at independent diesel emissions testing facilities. Find a list of independent diesel stations here.

The following rules apply to diesel-powered vehicles:

  • Diesel vehicles are exempt for four (4) years if they are purchased brand new.
  • Vehicles less than 10 years old are inspected biennially after the exemption period.
  • Vehicles more than 10 years old are inspected annually.
  • Heavy-duty vehicles, model year 2014 and newer, with a gross vehicle weight of 24,000 or more are exempt from emissions testing (if they are purchased brand new) for the first six (6) years, and then tested every two (2) years until they reach their 10th year. After that, these vehicles require inspection every year. 

When Are Air Care Stations Open?

Monday to Friday, 8 am to 5:30 pm, Saturdays, 8 am to 1 pm.
Closed Sundays and state holidays. 

How Long Does an Inspection Take?

The actual inspection time is generally less than 20 minutes. However, the wait in the queue varies greatly. Please check the Locations & Maps page for up-to-date wait times.

How Much Does an Inspection Cost?

$25 - Vehicles eight (8) years old back to model year 1982 (biennial inspection)
$25 - RapidScreen roadside emissions test (biennial inspection)
$15 - Vehicles model years 1981 and older (annual inspection)
$20 - Vehicle Identification Number (VIN) verification  

Air Care Colorado accepts cash, checks and Visa MasterCard and Discover. Please make checks payable to Air Care Colorado.

** Vehicle sellers must provide either a new Certificate of Emissions Compliance (obtained after passing the emissions test) or an emissions inspection voucher at the time of sale.

Where are Air Care Colorado Inspection Stations Located? 

There are 18 conveniently located Air Care Colorado emissions inspection stations. Visit the Air Care Colorado Locations & Maps page on this website for directions and wait times.  

What Do I Need to Bring to the Inspection Station?

Just the vehicle. No paperwork necessary.

What Types of Tests are Done?

On-board diagnostics (OBD) - non driving, plug-in test

Every vehicle built for sale in the United States since model year 1996 comes equipped with on-board diagnostics (OBD). This feature helps to determine problems with vehicles, allowing for quicker repairs and improved performance.

Air Care Colorado tests the following components of a vehicle's OBD system:

  • "Check Engine" light
    The primary way a vehicle's OBD system communicates. Inspectors check to make sure the light bulb and circuit are functioning properly.
  • Command status
    Inspectors check to see if the OBD system detects any emissions-related problems and if possible commands the "Check Engine" light to turn on.
  • Diagnostic trouble codes
    These codes can describe the exact issue(s) a vehicle is experiencing.

I/M 240 Dynamometer - driving, treadmill-type test

The vehicle is placed on large rollers and a four-minute road simulation test is performed while the vehicle is being "driven."

These vehicles, if equipped with OBD systems, are also tested using the OBD plug-in test. However, the OBD test is advisory only. If the OBD system test detects problems, through diagnostic trouble codes or a lit "Check Engine" light, it will be noted on the Vehicle Inspection Report, but the vehicle will not fail for an OBD problem alone.

If a vehicle passes the I/M 240 but had an OBD Advisory Fail, it is wise to promptly seek further diagnosis and repairs to improve vehicle performance, save money, avoid failing the next emissions inspection and prevent more serious problems.

Idle Test

Vehicles model year 1981 and older receive an idle test.

Alternative tests

Sometimes either the required OBD or I/M 240 tests can not be performed due to a variety of issues including, vehicle configuration, a problem preventing the vehicle’s computer from communicating with the test equipment, the vehicle not being "ready" to be tested, or the vehicle being randomly selected to receive an alternative test to ensure the quality of the various inspection types. Therefore, alternative I/M 240 or OBD inspections may be performed.

Gas Cap Test

A properly functioning gas cap is an essential part of the vehicle's emissions control system. A missing or leaking gas cap will cause the vehicle to fail the emissions inspection. A full retest is required when the vehicle fails initially for a missing or defective gas cap. Replacing the gas cap will affect the vehicle's emissions control capability and may increase its tailpipe emissions.

RapidScreen roadside testing

RapidScreen is Air Care Colorado's roadside emissions testing program. It is an alternative to standard testing at emissions testing stations, allowing motorists to have their vehicle's emissions screened in less than a second as they drive past a RapidScreen emissions testing system. For more information, see this website's RapidScreen section.

What are "Readiness" Monitors?

There are up to 11 "Readiness" monitors in a vehicle that allow the vehicle’s OBD system to monitor for potential emissions problems. Some of these monitors run whenever the vehicle is operating while others run only periodically. Once a monitor has run through its cycle, it is set to “Ready” indicating that the system’s self-evaluation is complete.

Part of Colorado’s OBD emissions test requires certain monitors to be set to “Ready” to ensure the system has properly performed this self- evaluation. All OBD-inspected vehicles must have Catalytic Converter(s), Oxygen Sensor(s), and Heated Oxygen Sensor(s) (if so equipped) monitors set to “Ready” in order to be inspected. 

Specific conditions must be met while driving for the Readiness Monitors to be set to “Ready”. Some vehicle manufacturers provide specific driving procedures to set the necessary monitors to ready.

What is a Vehicle Unable to Test Form? 

If given a Vehicle Unable to Test form it means the vehicle was not testable for the reason(s) checked on the form. These can include unsafe, inaccessible, or malfunctioning equipment. The problem(s) must be repaired before the vehicle can be inspected.

Why Did My Vehicle Fail Its Inspection?

Vehicles can fail for a number of reasons. Here are some common ones:

  • The vehicle's "Check Engine" light is on.
  • The vehicle's OBD system detected problems thereby setting "Trouble Codes".
  • The vehicle exceeded the allowable limits for HC, CO, and or NOx.
  • The vehicle's emissions control equipment is either missing or malfunctioning.
  • The vehicle's gas cap is either missing or malfunctioning.
  • The vehicle is emitting visible smoke
See the Air Care Colorado Brochure "My Vehicle Has Failed Its Emissions Test ... Now What Do I Do?" for more information.

What Do I Do If My Recently Purchased Used Vehicle Fails?

If a newly purchased vehicle fails its emissions inspection, consumers have three (3) business days, beginning the day after the motorist takes possession of the vehicle, to return it to the dealer/seller for repairs or repurchase. "Business days" are defined as Monday through Saturday, with the exception of state holidays. The dealer is required by law to repair, pay a third party to repair or to repurchase the failed vehicle. The dealer will explain which of these options it has chosen within three (3) business days after the vehicle has been returned to the dealer.

If the failed vehicle is not returned within the initial three-day period, the dealer will be relieved of responsibility to repair or repurchase the vehicle for compliance with the emissions program.

How Do I Renew My Vehicle Registration?

You may need an emissions test every two years if your light-duty (8,500 pounds or less gross vehicle weight) gasoline-powered vehicle is registered to a mailing address in the Automobile Inspection and Readjustment (AIR) Program area (i.e., all of Boulder, Broomfield, Denver, Douglas and Jefferson counties, and parts of Adams, Arapahoe, Larimer and Weld counties). If you passed the emissions test last year, then you probably don’t need another test until next year.

Vehicles model year 1981 and older need an emissions inspection every year.

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

The best way to know if a vehicle needs an inspection is from the vehicle registration renewal postcard. It comes in the mail about two weeks before the renewal is due, and it will indicate one of the following:

Due by the end of the month in which your current registration expires.

Vehicle was "clean screened" through the RapidScreen Roadside Emissions Testing program.


Some vehicles do not require an emissions test:

  • Vehicles that are less than eight model years old.
  • All-electric vehicles (hybrid-electric vehicles are inspected after 7 years).
  • Collector vehicles (model year 1975 and older).
  • Horseless carriages, street rods, farm vehicles, kit cars, and motorcycles.

What Can I Do If My Vehicle Fails and I've Spent At Least $715 On Repairs?

Apply to the Colorado Department of Revenue for a waiver.

What is a Waiver and How do I Apply?
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 emissions program at 303-205-5603. Please have the most recent failed emissions inspection report available before calling. 

Where Can I Report a Smoking Vehicle?

You can report vehicles with excessive smoke to the Colorado Department of Public Health and Environment's Smoking Vehicle Hotline at 303-692-3211, or email Please include the vehicle's license plate number and, if possible, whether it's gasoline- or diesel-powered. This hotline is only for reporting smoking vehicles with Colorado license plates, and not out-of-state plates or temporary tags.

Collector vehicles

There are several "collector's item" categories depending the age of the vehicle. The requirements are as follows:

  • Vehicles model years 1975-and-older can be registered as "collector's items" with no emissions inspection requirement  or mileage restriction. However, if the vehicle is not specifically registered as a "collector's item," an emissions inspection is required every year. 


  • Vehicles model year 1976 to 1984 that have been registered as a "collector's item" prior to Sept. 1, 2009, and the registration has never lapsed or expired, do not require an emissions inspection and there is no mileage restriction. If the vehicle has not previously been registered as a "collector's item," an emissions inspection is required every year.


  • Vehicles at least 32 years old are eligible for "collector's item" registration. However, in order to register as a "collector's item," these vehicles will require an initial emissions inspection and then must be inpsected every five years thereafter at the time of registration renewal. These vehicle have a mileage restriction limiting driving to no more than 4,500 miles per year. If the vehicle is being registered in a county that does not require an emissions inspection, only the mileage restriction applies.

If you have any questions or concerns regarding "collector's item" registration, please contact the Colorado Department of Revenue Emissions Program at 303-205-5603.

What Are The Emissions Inspection Requirements for Vehicles That Commute Into The Program Area From A Non Program Area?

If a vehicle is registered to an address outside the Automobile Inspection and Readjustment (AIR) program area but is driven at least 90 days a year into the program area for employment or school, then it falls under the requirements for emissions inspection outlined above.

What Do I Do if My Vehicle is Out of State When its Emission Inspection and Registration is Due?

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.