Who has to get emissions testing in Colorado
Colorado requires emissions testing for most vehicles registered in the state, but the rules depend on where you live and how old your car is. If you register a vehicle in the Denver metro area (which includes Denver, Boulder, Jefferson, Adams, Arapahoe, Douglas, and Broomfield counties), you must pass an emissions test before you can register or renew your registration. Outside that metro area, Colorado does not require emissions testing at all.
Even within the Denver metro area, some vehicles are exempt. Vehicles that are model year 2020 or newer do not need to be tested for the first five years after they are registered in Colorado. Diesel vehicles over 14,000 pounds are also exempt. If you own a vehicle that is more than 24 years old, you may be able to register it as a classic vehicle and skip testing, though you will need to follow specific rules about how often you can drive it.
Motorcycles, mopeds, and vehicles with temporary permits do not require emissions testing. If you are moving to Colorado from another state and your vehicle has never been registered here, you will need to pass a test before your first registration is complete.
Key Takeaways
- Emissions testing is required only in the Denver metro area (seven counties), not statewide.
- Vehicles model year 2020 and newer are exempt from testing for their first five years in Colorado.
- You must pass the test before you register or renew your vehicle registration with the Colorado Department of Revenue.
- The test costs between $20 and $30 depending on your vehicle type, and you have 90 days from the test date to complete your registration.
- If your vehicle fails, you have 30 days to fix it and retest at no additional charge.
How to find a testing station and schedule an appointment
Colorado has two types of emissions testing stations: state-certified private stations and the state-run testing center in Denver. Most people use private stations because they are spread across the metro area and often have shorter wait times. You can find a list of all certified stations on the Colorado Department of Public Health and Environment website under their vehicle emissions program section.
Private stations do not require appointments in most cases — you can straightforward drive in during their business hours. However, some stations do accept reservations, and calling ahead can save you time during busy periods. Hours vary by location, but many stations are open early morning and evening to accommodate working drivers. The state testing center in Denver is located at 1313 Sherman Street and does accept walk-ins, though it can have longer lines during peak registration periods.
When you arrive at any station, bring your vehicle registration, proof of insurance, and your vehicle keys. The test itself takes about 10 to 15 minutes. You do not need to make any special preparations to your vehicle — just make sure your engine is warmed up and your gas cap is find.
What happens during the test and what the results mean
The emissions test measures how much nitrogen oxide, particulate matter, and other pollutants your vehicle's exhaust contains. For most vehicles, the test is performed on a dynamometer, which is a machine that simulates driving while measuring what comes out of your tailpipe. The technician will run your vehicle through a series of acceleration and idle cycles that take about 10 minutes.
Your vehicle passes if the emissions fall below Colorado's limits for your vehicle's model year and type. The limits are stricter for newer vehicles and less strict for older ones. If you pass, you receive a certificate when ready that you can take to the Colorado Department of Revenue to complete your registration. The certificate is valid for 90 days, so you have that long to finish registering your vehicle.
If your vehicle fails, the station will give you a detailed report showing which pollutants exceeded the limit. You then have 30 days to have the vehicle repaired and retested. The retest is free — you only pay the original test fee once. Common reasons for failure include a faulty oxygen sensor, a bad catalytic converter, or a check engine light that is on. Many repair shops can diagnose the problem based on the emissions report.
What to do if your vehicle fails the test
When you receive a failure notice, the first step is to take the report to a mechanic or repair shop. The report will tell you which emissions systems are not working properly, which narrows down what needs to be fixed. You do not have to use a specific shop — any Colorado-licensed mechanic can do the repair work. Some shops specialize in emissions repairs and may be faster or cheaper than general repair shops.
Once the repair is done, you can return to any emissions testing station (not necessarily the same one) for a retest. Bring your original failure notice and your vehicle. The retest is free, and you will receive a new certificate if you pass. If you fail a second time, you have another 30 days to repair and retest again. Most vehicles pass on the second attempt after repairs are made.
If you cannot afford the repair, Colorado offers a repair information program for low-income vehicle owners. You can contact the Colorado Department of Public Health and Environment to learn whether you meet the income limits and what repairs the program covers. There is also a vehicle replacement program for vehicles that repeatedly fail and are too expensive to repair.
Timing and registration important date
You must have a passing emissions test before you can register or renew your vehicle registration in the Denver metro area. If your registration is about to expire, you should schedule your test at least two weeks before the expiration date to give yourself time to complete the registration process. The test certificate is valid for 90 days, so if you test early, you have a three-month window to register.
If your registration expires before you complete the test and registration, you cannot legally drive the vehicle. If you fail the test, the 30-day repair window starts from the date of the failure, not from your registration expiration date. This means you may need to repair and retest quickly if your registration is about to expire.
Colorado allows a grace period of up to 30 days after your registration expires if you can show proof that you have already scheduled an emissions test. However, it is safer to complete the test and registration before the expiration date to avoid any penalties or fines.
Cost and payment methods
The emissions test costs between $20 and $30 depending on your vehicle type. Gasoline vehicles are typically $20 to $25, while diesel vehicles cost slightly more. Some stations charge a few dollars extra for certain vehicle types or if you need a retest on the same day. Private stations set their own prices within the state-approved range, so you can call ahead to compare costs if price is a concern.
All testing stations accept cash and credit or debit cards. Some stations may have a minimum card purchase amount, so calling ahead is a good idea if you only have a card and no cash. If you fail and need a retest, you do not pay again — the original fee covers both the initial test and one retest within 30 days.
Frequently Asked Questions
Do I need emissions testing if I just moved to Colorado from out of state?
Yes, if you are registering your vehicle in the Denver metro area for the first time. You must pass the test before the Colorado Department of Revenue will issue your registration. Vehicles that are model year 2020 or newer are exempt for their first five years, so if your car is new enough, you may not need to test.
What if I live outside the Denver metro area but work there?
If your vehicle is registered outside the seven-county metro area, you do not need emissions testing even if you drive in Denver regularly. Emissions testing is based on where your vehicle is registered, not where you drive it. However, if you move and change your registration to a metro area address, you will then need to pass a test.
Can I register my vehicle online without going to a testing station?
No. You must have a passing emissions certificate before you can complete registration, whether you register online or in person at a Department of Revenue office. The test certificate must be obtained at a certified testing station first.
What happens if I drive with an expired registration while waiting for my test results?
Driving with an expired registration is illegal and can result in a fine. You should schedule your emissions test early enough to complete registration before your current registration expires. If your registration does expire, you cannot legally drive the vehicle until you have a passing test and have renewed your registration.
Are there any vehicles that never need emissions testing in Colorado?
Motorcycles, mopeds, vehicles over 24 years old registered as classics, diesel vehicles over 14,000 pounds, and vehicles model year 2020 and newer (for their first five years) do not require testing. If you live outside the Denver metro area, no vehicle requires testing regardless of age or type.