What the Air Care test measures and why Colorado requires it

Colorado's Air Care program tests whether your vehicle's emissions system is working properly. The test measures what comes out of your tailpipe — mainly nitrogen oxides, particulate matter, and hydrocarbons — to make sure your car isn't releasing too much pollution into the air. If your vehicle passes, you get a certificate that proves it met the state's standards for that year.

Not every Colorado county requires the test. The program runs in the Denver metro area and a few surrounding counties where air quality has historically been a concern. If you live in one of those counties and your vehicle is registered there, you'll need to pass Air Care before you can renew your registration. Vehicles that are too old or too new, diesel trucks, and motorcycles are typically exempt.

The test itself takes about 10 minutes and costs around $20 to $30, though the exact fee varies by testing station. You can find a list of certified Air Care stations on the Colorado Department of Transportation website.

Key Takeaways

  • Air Care tests your vehicle's emissions system to measure pollution from your tailpipe and is required in Denver metro and a few surrounding counties before you renew your registration.
  • The test takes about 10 minutes, costs $20 to $30, and you can schedule it at any certified Air Care station in your county.
  • Vehicles older than a certain year, brand new vehicles, diesel trucks, and motorcycles are usually exempt from the test.
  • If your vehicle fails, you have a grace period to repair it and retest before your registration expires, and some repairs may be covered by the Air Care Repair information Program if your household income is below a certain threshold.

How to find a testing station and schedule your test

You can locate Air Care stations through the Colorado Department of Transportation's website or by calling 1-888-AIRCARE. The site lets you search by county and shows you each station's hours and phone number. Most stations are open during regular business hours, and many accept walk-ins, though calling ahead to confirm availability is a good idea during busy seasons.

When you call or visit, have your vehicle's registration and license plate number ready. You don't need to make an appointment at most stations, but some do accept them. Bring your keys and be prepared to stay while the test runs — you'll need to be in the car during the emissions measurement.

What happens during the test

The technician will connect a probe to your vehicle's tailpipe and run your engine through a series of speeds and loads to measure what's being emitted. The whole process takes roughly 10 minutes. You'll sit in the driver's seat while this happens. The test is non-invasive — nothing is done to your vehicle's engine or systems.

At the end, you'll get a result on the spot. If you pass, you receive a certificate that you can use to renew your registration. If you fail, the technician will give you a report showing which emissions were too high. This report is useful when you take your vehicle to a mechanic, because it tells them specifically what system needs attention.

What to do if your vehicle fails the test

A failure doesn't mean you can't renew your registration when ready. Colorado gives you a grace period — usually until your registration expires — to repair your vehicle and retest. During that time, you can drive legally while you're working on the repairs.

Common reasons for failure include a faulty oxygen sensor, a malfunctioning catalytic converter, or problems with the fuel injection system. A mechanic can diagnose the exact issue using the emissions report you received. Repairs can range from $100 to several hundred dollars depending on what needs fixing.

If the repair cost is a barrier, the Air Care Repair information Program may help. This program covers some repair costs for vehicles that fail the test, but only if your household income is below a certain level. You can ask the Air Care station for information about this program, or contact the Colorado Department of Transportation directly.

Which vehicles are exempt from Air Care testing

Vehicles registered in Colorado are exempt from Air Care if they fall into certain categories. Generally, vehicles manufactured before a specific model year (this year changes periodically) are exempt because older emissions systems are held to different standards. Brand new vehicles, usually those from the current model year, are also exempt for their first few years of registration.

Diesel-powered vehicles, motorcycles, and vehicles with a Gross Vehicle Weight Rating above a certain threshold are typically exempt as well. If you're unsure whether your vehicle is exempt, the Air Care website has a tool where you can enter your vehicle information and find out when ready.

How Air Care results affect your registration renewal

When you renew your vehicle registration in Colorado, the state checks whether you've passed Air Care if your vehicle is required to do so. If you pass the test, renewal is straightforward — you can complete it online, by mail, or in person at your local county clerk's office. The Air Care certificate is valid for one year from the date you pass.

If you haven't passed Air Care by the time your registration expires, you won't be able to renew until you do. This is why it's important to test early in your registration period rather than waiting until the last moment. If your vehicle fails and you're in the grace period, you can still renew your registration, but you'll need to show proof that you've scheduled a retest or that you're working on repairs.

Preparing your vehicle for the Air Care test

You don't need to do much to prepare. Make sure your vehicle has been driven recently so the engine is warm when you arrive — a cold engine can sometimes produce different emissions readings. Check that your gas cap is tight, because a loose cap can trigger a failure. If your check engine light is on, have a mechanic look at it before testing, because that light often indicates an emissions-related problem.

Beyond that, just bring your registration and keys. The test measures your vehicle's actual performance, so there's no way to "cheat" or artificially improve results. If your vehicle is in good working order, it should pass.

Frequently Asked Questions

Can I test my vehicle in a different county than where it's registered?

No. You must test in the county where your vehicle is registered. If you've recently moved to a different county, you'll need to update your registration first, then test in your new county if it's part of the Air Care program.

What if I fail the test but can't afford to fix my vehicle right away?

You have a grace period until your registration expires to make repairs and retest. During that time, you can drive legally. If repair costs are a barrier, ask the Air Care station about the Repair information Program, which may cover some expenses if your household income qualifies.

Do I need to test every year?

Yes, if your vehicle is registered in an Air Care county and is not exempt. You must pass the test before you renew your registration each year. The certificate is valid for one year from the test date.

What if my vehicle has a check engine light on?

A check engine light usually means your vehicle will fail the Air Care test because it often signals an emissions system problem. Have a mechanic diagnose the issue before you test. Once the problem is fixed and the light goes off, your vehicle is more likely to pass.

How long does the Air Care certificate last?

Your Air Care certificate is valid for one year from the date you pass the test. You'll need to retest the following year before you renew your registration again.