How to find an emissions testing station near you

Colorado operates two separate emissions testing programs depending on where you live. The Denver Metro area (which includes Denver, Boulder, Fort Collins, and surrounding counties) requires a more rigorous test called the IM240. The rest of Colorado uses the OBD (On-Board Diagnostics) test, which is simpler and faster. Your location determines which test you need and which stations you can visit.

The Colorado Department of Public Health and Environment (CDPHE) maintains the official list of all licensed testing stations. You can search by county or city on their website at cdphe.colorado.gov — look for the "Emissions Testing" section under air quality. The search tool shows you the station name, address, phone number, and hours. Many stations are independent repair shops, not just large chains.

You do not need an appointment at most Colorado stations, but calling ahead is smart. Some locations get busy during peak hours (typically late afternoon and Saturday mornings), and a few do require reservations. The test itself takes 10 to 20 minutes for OBD stations and 20 to 30 minutes for IM240 stations in the Denver Metro area.

Key Takeaways

  • The CDPHE website lists all licensed testing stations by county, with phone numbers and hours you can call to confirm availability.
  • Denver Metro counties use the IM240 test; all other Colorado counties use the OBD test, and you can only use stations licensed for your area's test type.
  • Most stations do not require an appointment, but calling ahead can save you a wait, especially on Saturday mornings.
  • Testing costs between $20 and $35 depending on the station and test type, and you pay the station directly — there is no state fee.

Denver Metro IM240 testing stations

The Denver Metro area includes Adams, Arapahoe, Boulder, Broomfield, Denver, Douglas, Jefferson, and Weld counties. These counties require the IM240 dynamometer test, which is more thorough than the OBD test used elsewhere in the state. The IM240 puts your vehicle on a rolling dynamometer and measures emissions under simulated driving conditions.

Licensed IM240 stations in the Denver Metro area are spread across the region. Large chains like Firestone, Midas, and Valvoline operate some locations, but many independent repair shops and dedicated emissions testing centers also hold licenses. The CDPHE website filters results by county, so you can narrow your search to the county where your vehicle is registered.

IM240 testing typically costs $25 to $35 per vehicle. The test takes 20 to 30 minutes, and you receive your results on the spot. If your vehicle passes, you get a certificate that is valid for two years. If it fails, the technician will provide a printout showing which emissions systems did not meet standards.

OBD testing stations in the rest of Colorado

All Colorado counties outside the Denver Metro area use OBD testing, which reads your vehicle's onboard diagnostic system. This test is faster and less expensive than IM240 because it does not require a dynamometer. The technician plugs a scanner into your vehicle's OBD port (usually under the steering wheel) and checks whether your emissions control systems are functioning.

OBD stations are more widely available than IM240 stations because the equipment is less specialized. You will find them at independent repair shops, tire shops, and some gas stations across rural and suburban Colorado. The CDPHE website lists all licensed locations by county — search for your county to see what is available near you.

OBD testing costs $15 to $25 and takes 10 to 15 minutes. You get your results when ready. A passing certificate is valid for two years. If your vehicle fails, you will receive a report showing which emissions systems triggered the failure code.

What to bring and what to expect

Bring your vehicle registration and a valid photo ID. The technician will verify that the vehicle you are testing matches your registration. You do not need to bring your inspection sticker or any service records — the test itself tells the technician what your vehicle's emissions status is.

Before you go, make sure your vehicle's check engine light is off. If the light is on, your vehicle will fail the test automatically. If you recently had work done on your emissions system, drive the vehicle for at least 100 miles before testing so the onboard computer can complete its self-diagnostic cycle.

The technician will ask you to start the engine and may ask you to turn it off and on a few times during the test. For IM240 testing in the Denver Metro area, you will drive on the dynamometer while the technician monitors your emissions output. For OBD testing, the process is entirely passive — you sit in the vehicle while the scanner reads your system.

What happens if your vehicle fails

A failing result does not mean you cannot drive your vehicle. You have time to get repairs done and retest. Colorado law allows you to retest at any licensed station without waiting a set period — you can retest the same day if you want. However, you will pay the testing fee again for each retest.

The failure report will show you which emissions systems are not working correctly. Common failures include a faulty oxygen sensor, a problem with the catalytic converter, or an issue with the evaporative emissions system. Take the failure report to a repair shop — they can use it to diagnose what needs to be fixed.

Once repairs are complete, you can return to any licensed testing station to retest. Many stations will retest you at the same location where you failed, but you are not required to use the same station. Keep your passing certificate once you get it — you will need to show it when you renew your vehicle registration.

Finding stations by specific county

The CDPHE website search tool is the fastest way to find stations in your county. If you live in Denver, search "Denver emissions testing" on the CDPHE site and you will see all IM240 stations in Denver. If you live in a county outside the Denver Metro area — such as El Paso, Larimer, or Mesa County — search that county name and you will see all OBD stations licensed there.

Some counties have only a few licensed stations, so your options may be limited. If the nearest station is far away, call ahead to confirm they are open and ask about wait times. A few stations in rural areas operate by appointment only, so a phone call can save you a wasted trip.

If you cannot find a station in your county on the CDPHE website, contact your county health department directly. They can tell you whether there are licensed stations in your area or whether you need to travel to a neighboring county.

Frequently Asked Questions

Can I test my vehicle at any station in Colorado, or does it have to be in my county?

Your vehicle must be tested at a station licensed for your county's test type. If you live in a Denver Metro county, you must use an IM240 station. If you live outside the Denver Metro area, you must use an OBD station. You cannot cross between the two test types.

What if there are no testing stations near me?

Call your county health department or the CDPHE directly. They can tell you whether stations exist in your county or which neighboring county has the nearest option. Some rural counties have very few stations, and you may need to travel 30 to 60 minutes to the nearest one.

Do I need to make an appointment, or can I just show up?

Most stations accept walk-ins, but calling ahead is smart. Some locations get busy on Saturday mornings and late weekday afternoons. A few stations in rural areas require appointments. Calling the station directly takes two minutes and can save you a wait.

How long is my passing certificate good for?

A passing emissions certificate is valid for two years from the test date. You need a current certificate to renew your vehicle registration. If your certificate expires before you renew, you will need to retest before you can complete registration renewal.

Can I retest the same day if I fail?

Yes. Colorado does not require you to wait between tests. You can retest at any licensed station the same day you fail, though you will pay the testing fee again. Many people get repairs done and retest within a few days.