What Fort Collins emission testing requires

Fort Collins requires emission testing for most vehicles registered in the city, with the test happening every two years for cars model year 1981 and newer. The test measures what comes out of your tailpipe—specifically nitrogen oxides, particulate matter, and hydrocarbons—to confirm your vehicle meets Colorado air quality standards. You cannot renew your vehicle registration without a passing emissions test result on file.

The actual test takes about 10 to 15 minutes. A technician plugs a diagnostic scanner into your vehicle's onboard computer port (located under the steering column on most cars) and runs it through a series of acceleration and idle cycles on a dynamometer—a machine that simulates driving without moving the car. The scanner reads what your engine is producing and compares it to the legal limits for your vehicle's model year and engine type.

You do not need an appointment at most testing stations, though calling ahead can save you a wait. The test costs between $20 and $30 depending on the station. You'll need your vehicle registration and proof of insurance, though the technician is mainly checking that your vehicle is registered in Colorado.

Key Takeaways

  • Fort Collins emission testing is required every two years for vehicles model year 1981 and newer, and you cannot renew registration without a passing result.
  • The test plugs into your vehicle's onboard computer and measures tailpipe emissions against Colorado air quality standards in about 10 to 15 minutes.
  • Testing stations in Fort Collins include the Colorado Department of Transportation's official station and several private repair shops certified to perform the test.
  • A vehicle that fails the test can be retested when ready at no additional cost if repairs are made, or you can request a waiver if repair costs exceed a certain threshold.
  • Diesel vehicles and motorcycles have different testing requirements or are exempt entirely, so check your vehicle type before scheduling.

Where to get tested in Fort Collins

The Colorado Department of Transportation (CDOT) runs an official emissions testing station in Fort Collins at 215 North College Avenue, Building 500. This is a state-run facility that performs only the test itself—no repairs—so you know the result is independent. Hours vary by season; the station typically operates Monday through Friday during business hours, with extended hours in spring and fall when testing volume is highest.

Private repair shops and tire shops throughout Fort Collins are also certified to perform emissions testing. These include national chains like Firestone and local independent shops. The advantage of a private station is convenience and location; the disadvantage is that if your vehicle fails, the shop may pressure you toward repairs they perform themselves. You are not required to use the same shop for repairs that you used for testing.

You can find a list of all certified testing stations on the Colorado Department of Public Health and Environment website under the Air Pollution Control Division. The list includes addresses, phone numbers, and hours. Calling ahead is worth the minute it takes, because some stations close for lunch or have seasonal hour changes.

What happens if your vehicle fails

A failed test means your vehicle's emissions are above the legal limit for at least one pollutant. The technician will give you a printed report showing which emissions exceeded the standard and by how much. This report is your starting point for understanding what might be wrong.

Common reasons for failure include a faulty oxygen sensor, a malfunctioning catalytic converter, a clogged air filter, or an engine control module that is not reading sensor data correctly. Some of these are cheap fixes—an air filter is $15 to $40—and others are expensive, like a catalytic converter replacement, which can run $800 to $2,500 depending on your vehicle.

Colorado law allows you to request a repair cost waiver if the repairs needed to pass the test would cost more than a certain amount. As of 2024, that threshold is $375 for most vehicles. If a repair shop gives you a written estimate showing the cost exceeds this amount, you can request a waiver from the Colorado Department of Public Health and Environment, and your vehicle can be registered without passing the test. You will need to retest the following year, but the waiver gives you time to save or plan the repair.

Retesting after repairs

If you repair your vehicle and want to retest, you can return to any certified station when ready. There is no additional fee for a retest within a certain window—typically 30 days from the original test date, though this varies by station. Some stations waive the retest fee entirely if you bring the original failed test report.

Before you retest, make sure the repair shop has cleared any diagnostic trouble codes from your vehicle's computer. A code that triggered the failure will cause the test to fail again even if the underlying problem is fixed. Most repair shops do this automatically, but it is worth asking.

If your vehicle passes the retest, the new result is sent to the Colorado Department of Motor Vehicles automatically, and your registration can be renewed. If it fails again, you have the same options: make more repairs, request a waiver, or explore whether the original diagnosis was correct by taking the vehicle to a different shop for a second opinion.

Vehicles exempt from Fort Collins testing

Diesel vehicles are tested under a separate program with different standards and are handled at different stations. Motorcycles are exempt from emissions testing in Colorado entirely. Vehicles model year 1980 and older are also exempt, as are electric vehicles and plug-in hybrids.

Vehicles registered outside Colorado but driven in Fort Collins temporarily do not need to be tested. However, if you move to Fort Collins and register your vehicle in Colorado, you will need a passing emissions test before or at the time of registration, regardless of where the vehicle was previously registered.

If you are unsure whether your vehicle is exempt, the easiest check is to call the CDOT testing station or look up your vehicle's model year and fuel type on the Colorado Department of Public Health and Environment website. A two-minute phone call can save you a wasted trip.

Preparing your vehicle before testing

You do not need to do anything special to prepare for an emissions test, but a few straightforward steps can reduce the chance of failure. Make sure your check engine light is not on—if it is, the vehicle will fail the test automatically because the computer is detecting a problem. Have your air filter checked; a clogged air filter can cause higher emissions and is cheap to replace.

Drive your vehicle normally for at least 50 miles before testing. A vehicle that has been sitting or driven only short distances may not have gone through enough engine cycles for the computer to clear old diagnostic codes. This is especially true in winter or after a long period of infrequent driving.

Make sure your gas cap is tight and not cracked. A loose or damaged cap can trigger a fuel vapor leak code, which will cause a test failure. If your vehicle has had recent work done—spark plugs, fuel injector cleaning, or sensor replacement—wait a few days and drive it normally before testing to allow the computer to relearn and stabilize.

Understanding your test results

A passing test result shows that your vehicle's emissions are at or below the legal limit for all measured pollutants. The result is sent electronically to the Colorado Department of Motor Vehicles, and you can renew your registration when ready. You do not need to print anything or bring anything to the DMV; the result is already there.

A failing result shows which pollutant or pollutants exceeded the limit and by how much. The report will list nitrogen oxides (NOx), particulate matter (PM), and hydrocarbons (HC) separately. It will also show your vehicle's test category—whether it was tested as a gasoline vehicle, a heavy-duty vehicle, or another type—because the legal limits differ by category.

The test result also includes the vehicle's VIN, the test date, and the testing station's name. Keep this report if you plan to request a repair cost waiver or if you want to show it to a repair shop as documentation of what failed. Some shops will use this information to narrow down what to check first.

Frequently Asked Questions

Can I test my vehicle before my registration expires?

Yes. You can test up to 60 days before your registration expires. The result will be valid for two years from the test date, so if you test early, your next test will not be due until two years later. Testing early is a good idea if you know your vehicle might fail and want time to repair it without rushing.

What if I just moved to Fort Collins from another state?

You will need a passing emissions test before you can register your vehicle in Colorado. If your vehicle is currently registered in another state, get it tested at a Fort Collins station before you go to the DMV to transfer the registration. The test result must be dated after you moved to Colorado.

Do I have to use the CDOT station or can I use a private shop?

Either one is fine. The CDOT station is state-run and has no financial interest in repairs, so some people prefer it for that reason. Private shops are often more convenient and faster. The test result is equally valid from either location.

What if my vehicle has a check engine light on?

Your vehicle will fail the emissions test automatically if the check engine light is on, because the light means your vehicle's computer has detected a problem. Have the code read and the problem diagnosed before testing. Many auto parts stores will read the code for free.

How long does a passing result stay valid?

A passing emissions test result is valid for two years from the test date. You must retest before your registration expires, which is typically two years from the test date. If you test early, your next test is due two years from that earlier test date, not two years from your registration renewal date.