What Air Care Colorado Does and Who Needs It

Air Care Colorado is the state's vehicle emissions testing program, run by the Colorado Department of Public Health and Environment. If you live in one of Colorado's eight designated air quality areas — primarily the Denver metro region, but also parts of the Front Range and other counties — you must have your vehicle tested every two years (or annually if it fails). The test measures whether your vehicle's exhaust meets state and federal pollution standards.

Not all of Colorado requires emissions testing. If you live in a rural county outside the designated areas, you do not need to test. You can check whether your address falls in a testing area by entering your ZIP code on the Air Care Colorado website. The program exists because these regions have struggled to meet federal air quality standards, particularly during winter months when temperature inversions trap pollution near the ground.

You cannot renew your vehicle registration without a passing emissions test result (or a waiver, in specific circumstances). The test is separate from your safety inspection — you need both to register your vehicle in Colorado.

Key Takeaways

  • Air Care Colorado testing is required every two years in eight designated Colorado counties, primarily around Denver, but not statewide.
  • The test costs between $20 and $30 depending on your vehicle type and the testing station, and results are sent directly to the Colorado Division of Motor Vehicles.
  • You can test at any of roughly 140 Air Care Colorado stations across the state; the program does not assign you to a specific location.
  • Vehicles that fail can be retested at no charge within 30 days, and some repairs may may have access to for state rebates or information programs.
  • Older vehicles, high-mileage vehicles, and those with engine problems are most likely to fail; regular maintenance reduces failure risk.

How the Testing Process Works

When you arrive at an Air Care Colorado station, you will provide your vehicle identification number (VIN), license plate, and odometer reading. The technician will connect your vehicle to a dynamometer — a machine that simulates driving conditions while measuring emissions from your tailpipe. The test takes roughly 10 to 15 minutes and does not damage your vehicle.

The test measures two main pollutants: nitrogen oxides (NOx) and particulate matter (for diesel vehicles). Gasoline vehicles are tested for hydrocarbons and carbon monoxide as well. Your vehicle must stay within the state's limits for each pollutant based on its model year and engine type. Newer vehicles (generally 2010 and later) have stricter standards than older ones, but they also have better emissions control systems and rarely fail.

Results are transmitted electronically to the Colorado Division of Motor Vehicles within 24 hours. You will receive a receipt at the station showing whether you passed or failed. If you pass, you can renew your registration when ready. If you fail, you have 30 days to retest at no charge at any Air Care Colorado station.

Finding a Testing Station and Scheduling

Colorado has roughly 140 Air Care Colorado testing stations spread across the state, operated by independent repair shops, tire shops, and service centers. You can find stations near you by ZIP code or city on the Air Care Colorado website. Most stations operate during regular business hours, typically Monday through Friday, and some offer Saturday appointments.

You do not need an appointment at most stations — you can walk in during business hours. However, some stations accept appointments, and calling ahead can reduce wait times, especially during peak testing periods (September through November and January through March, when air quality concerns are highest). A few stations may have longer waits during these months.

The test fee varies slightly by station and vehicle type. Most tests cost $20 to $30. Diesel vehicles and vehicles with specialized equipment may cost slightly more. The fee is paid directly to the testing station, not to the state.

What Causes Emissions Test Failures

The most common reason for failure is a malfunctioning check engine light or emissions control system. This includes problems with the catalytic converter, oxygen sensors, fuel injectors, or the engine control computer. Vehicles with the check engine light illuminated will fail automatically, regardless of actual emissions levels, because the light indicates the emissions system is not functioning properly.

High mileage, poor maintenance, and age increase failure risk. Vehicles over 15 years old fail more often than newer ones, though many older vehicles pass if they have been maintained. Driving habits matter too — vehicles driven mostly on short trips or in stop-and-go traffic may have higher emissions than those driven regularly on highways.

A few failures are caused by straightforward issues: a loose gas cap, dirty air filter, or overdue oil change. Others point to more serious problems requiring repair. If you fail, the test report will indicate which emissions standard you exceeded, which can help a mechanic diagnose the issue.

Options After a Failed Test

You have 30 days to retest at no charge. Before retesting, you can have your vehicle repaired or serviced. Many drivers take their vehicle to a mechanic, describe the failure, and have the mechanic run a diagnostic scan to identify the problem. This diagnostic typically costs $50 to $150 and can pinpoint whether the issue is a sensor, the catalytic converter, or something else.

If repair costs are high, Colorado offers a few options. The Repair information Program provides rebates or grants to low-income vehicle owners whose repairs cost more than a certain threshold (the threshold changes year to year). You can also explore the Vehicle Retirement Program, which offers cash for vehicles that repeatedly fail and are not economical to repair — though this means surrendering the vehicle.

If you cannot afford repairs and do not meet income thresholds for information, you may be able to request a waiver from the Colorado Division of Motor Vehicles. Waivers are granted only in narrow circumstances — typically when you have attempted repairs in good faith, retested, and still failed. Waivers are not automatic and require documentation of your repair attempts.

Emissions Testing and Vehicle Registration Timing

Your emissions test result is valid for two years from the test date. You can test up to 60 days before your registration expires, so you do not have to wait until the last moment. Testing early gives you time to address a failure without rushing into expensive repairs or missing your registration important date.

If your registration expires before you test, you cannot legally drive the vehicle (except directly to a testing station). If you know your test is due soon, schedule it before your registration renewal notice arrives. This prevents a gap where your vehicle is unregistered and uninsured.

If you move out of a designated testing area, you no longer need to test, even if your current registration shows a test result. If you move into a testing area, you will need to test before your next registration renewal.

Frequently Asked Questions

What if I just bought a used car and it has not been tested recently?

The previous owner's test result is not transferred to you. You will need a new test before you can register the vehicle in your name. If the vehicle fails, you have 30 days to repair and retest. Some dealers offer a short grace period or will cover repairs, but this is not required by law.

Do hybrid or electric vehicles need to test?

Hybrid vehicles must test if they live in a designated area, though they rarely fail because their emissions are very low. Fully electric vehicles do not need to test because they produce no tailpipe emissions. Plug-in hybrids must test.

Can I test in a different county than where I live?

Yes. You can test at any Air Care Colorado station in the state, regardless of where you live or where your vehicle is registered. This is useful if you travel or prefer a station outside your when ready area.

What happens if I let my registration expire without testing?

Driving an unregistered vehicle is illegal and can result in fines and impound. If you realize your test is overdue, you can test when ready and then renew your registration. The state does not penalize you for the late test itself, only for driving without valid registration.

Is there a way to avoid testing altogether?

Only by living outside a designated testing area or by retiring the vehicle through the Vehicle Retirement Program. If you live in a testing area, testing is required every two years to register your vehicle. There is no exemption based on vehicle age, condition, or personal circumstances, except for the narrow waiver process described above.