Colorado emissions tests are required in most urban areas, not statewide

Colorado does not require an emissions test everywhere in the state. Instead, the Colorado Department of Public Health and Environment (CDPHE) requires testing only in counties that do not meet federal air quality standards. The Denver metro area, including Denver, Boulder, and surrounding counties, is the primary region where testing is mandatory. If you live in a rural county or one that consistently meets air quality targets, you will not need an emissions test to renew your vehicle registration.

The test itself checks whether your vehicle's exhaust meets Colorado's pollution limits. A certified emissions testing facility runs your car through a computerized diagnostic that measures nitrogen oxides, particulate matter, and other pollutants. The test takes about 10 to 15 minutes and costs between $25 and $35, depending on the facility.

You must pass the test before you can renew your vehicle registration. If you fail, you have options to repair your vehicle and retest, or in some cases, you may may have access to for a waiver or extension.

Key Takeaways

  • Emissions testing is required only in Colorado counties that fail to meet federal air quality standards, primarily the Denver metro area and surrounding regions.
  • Your vehicle must pass the test before you can renew your registration, and the test costs $25 to $35 at a certified facility.
  • If you fail, you can repair your vehicle and retest, or you may may have access to for a repair cost waiver if repairs exceed a certain threshold.
  • Vehicles older than model year 1968, diesel vehicles, and motorcycles are exempt from testing in most cases.
  • You can find a certified testing facility through the CDPHE website or by searching for "emissions testing near me" in your county.

Which Colorado counties require emissions testing

The Denver metro nonattainment area is the main region where testing is mandatory. This includes Denver, Adams, Arapahoe, Boulder, Douglas, Jefferson, and Weld counties. El Paso County (Colorado Springs area) also requires testing in some years depending on air quality data. The CDPHE updates the list of counties annually based on whether they meet the National Ambient Air Quality Standards (NAAQS).

If you are unsure whether your county requires testing, you can check the CDPHE Air Pollution Control Division website or call your county clerk's office when you renew your registration. They will tell you when ready whether a test is needed for your vehicle.

Vehicle types that are exempt from testing

Not every vehicle on the road must be tested. Motorcycles are exempt statewide. Vehicles manufactured before model year 1968 are also exempt, as are most diesel-powered vehicles (though some newer diesel trucks may be required to test under different standards).

Vehicles registered as antiques or classics may be exempt depending on their age and how often they are driven. If your vehicle falls into one of these categories, mention it when you go to renew your registration, and the county clerk will let you know whether a test is required.

How to find a testing facility and schedule an appointment

The CDPHE maintains a list of certified emissions testing stations on its website. You can search by county and city to find facilities near you. Many stations accept walk-ins, but calling ahead to confirm hours and current wait times is a good idea, especially during peak renewal periods (typically August through October).

When you arrive at the facility, bring your vehicle registration and a valid photo ID. The technician will run a diagnostic test on your vehicle's onboard computer system. The test does not require you to turn off the engine or leave the vehicle — you stay inside while the equipment reads your emissions data.

What happens if you fail the emissions test

If your vehicle fails, the testing facility will provide you with a report listing the specific pollutants that exceeded the limit. You then have the option to repair the vehicle and retest. The retest fee is usually the same as the initial test ($25 to $35), and you can retest at any certified facility.

Colorado offers a repair cost waiver program if the estimated cost to fix the problem exceeds a certain amount (typically $500 to $700, though this varies by year and vehicle type). If you may have access to for the waiver, you can register your vehicle without passing the test. To may have access to, you must obtain a written repair estimate from a mechanic and submit it to the testing facility or county clerk.

You also have the option to request a one-time extension if you are waiting for parts or repairs. Extensions are usually granted for 30 to 60 days. Contact your county clerk or the testing facility to request an extension before your registration expires.

Timing and registration renewal important date

Your vehicle registration renewal notice will arrive in the mail 30 to 60 days before your registration expires. The notice will indicate whether an emissions test is required. You must pass the test before you submit your renewal payment to the county clerk.

If you wait until the last week before expiration to test, you risk running out of time if you fail and need to repair your vehicle. Testing early (at least 4 to 6 weeks before expiration) gives you time to address any failures without rushing repairs or paying late fees.

What to do if you move to or from a testing county

If you move into a county that requires testing, you will need to pass a test before you renew your registration in that county. If you move out of a testing county to one that does not require testing, you will no longer need to test.

When you register your vehicle in a new county, the county clerk will tell you whether testing is required. If you have recently failed a test in your old county and are moving to a non-testing county, you do not need to repair the vehicle — the test requirement does not follow you.

Frequently Asked Questions

Do I need an emissions test if I just bought a used car in Colorado?

Yes, if you are registering it in a county that requires testing. The test is based on where you register the vehicle, not where you bought it. You will need to pass the test before the county clerk will process your registration.

Can I test my vehicle before my registration expires?

Yes. You can test up to 120 days before your registration expires. This gives you plenty of time to repair any failures and retest without rushing.

What if I fail the test twice?

You can retest as many times as you need. There is no limit on the number of retests. Each retest costs the standard fee ($25 to $35). If repairs are expensive, you may may have access to for the repair cost waiver instead of continuing to retest.

Do electric vehicles need an emissions test?

No. Electric vehicles produce zero tailpipe emissions and are exempt from testing in all Colorado counties.

What if the testing facility says my vehicle cannot be tested?

Some vehicles with severe mechanical problems or missing emissions equipment cannot be tested. If this happens, the facility will provide a written explanation. You can contact the CDPHE or your county clerk to discuss your options, which may include repair requirements or a waiver process.