What Colorado requires and who has to test

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, Colorado Springs, and Fort Collins), you must pass an emissions test every two years. Outside those areas, testing is required every three years. Vehicles that are model year 2007 or newer are exempt from testing statewide, as are diesel vehicles over 14,000 pounds.

Your registration renewal notice will tell you whether your vehicle needs testing. If you live in a non-attainment area and your car is older than 2007, you cannot renew your registration without a passing test result. The Colorado Department of Public Health and Environment oversees the program, but you do not deal with them directly — you go to a licensed testing station.

Key Takeaways

  • Denver metro residents must test every two years; everyone else tests every three years, unless the vehicle is 2007 or newer.
  • You need a passing test before you can renew your registration, and the test costs between $20 and $30 depending on the station.
  • Testing stations are private businesses licensed by the state, and you can find them through the Colorado Department of Public Health and Environment website or by searching locally.
  • If your vehicle fails, you have 60 days to repair it and retest at no additional charge at the same station.
  • Hybrid and electric vehicles are exempt from testing, and so are vehicles with fewer than 6,000 miles on the odometer.

Finding a testing station and scheduling

Colorado does not run a centralized booking system. Instead, you find a licensed testing station near you and call or visit to schedule an appointment. The Colorado Department of Public Health and Environment maintains a searchable list of stations on its website, organized by county. You can also search online for "emissions testing near me" and filter for Colorado-licensed stations.

Wait times vary by location and season. Stations in the Denver area tend to be busier in the months before registration renewal important date. Many stations accept walk-ins, but calling ahead to confirm hours and current wait times saves a trip. Some stations are open early morning or evening to accommodate work schedules.

What happens during the test

The test itself takes 10 to 15 minutes. A technician will plug a diagnostic scanner into your vehicle's onboard computer port (located under the steering wheel on most cars) and run a series of checks. The scanner reads your vehicle's emissions control systems and compares the results to Colorado standards. You do not need to do anything except have your keys and registration handy.

The technician will also perform a visual inspection to confirm that your catalytic converter and other emissions equipment are present and not obviously damaged. If your check engine light is on, the test will likely fail because the light indicates a problem with the emissions system. You can have the light diagnosed and repaired before retesting.

Costs and what to expect if you fail

A single emissions test costs between $20 and $30, depending on the station. This is a one-time fee per test; there is no state fee on top of the station's charge. If you pass, you receive a certificate or digital record that you present when you renew your registration. If you fail, the station will give you a detailed report showing which emissions standards your vehicle did not meet.

You have 60 days from the test date to repair your vehicle and return to the same station for a retest at no charge. If you go to a different station, you will pay the full testing fee again. Keep your failed test report — it documents what needs to be fixed and helps a mechanic diagnose the problem. Common failures involve the catalytic converter, oxygen sensors, or the fuel system.

Repairs and retesting after a failure

If your vehicle fails, take the test report to a mechanic and have them diagnose the specific problem. The report will list which emissions standards were not met, which narrows down what systems need attention. Repairs can range from $100 to $1,000 or more depending on what failed — a new oxygen sensor might cost $200, while a catalytic converter replacement can exceed $800.

After repairs, return to the same testing station within 60 days for a free retest. Bring your repair receipts if you have them, though the station does not require them to retest. If you pass the second time, you get your certificate and can renew your registration. If you fail again, you have another 60 days to make additional repairs and retest.

Exemptions and special cases

Vehicles model year 2007 and newer do not need to test in Colorado, regardless of where you live. Diesel vehicles over 14,000 pounds are also exempt. Hybrid and electric vehicles are exempt statewide. New vehicles (fewer than 6,000 miles on the odometer) are exempt for their first registration.

If you are moving to Colorado from another state, your vehicle must pass an emissions test before you can register it here, even if it is newer than 2007. The test is the same as the regular biennial or triennial test. If you are moving out of state, you do not need to pass a final test — your Colorado registration straightforward expires.

Frequently Asked Questions

Can I renew my registration online if I have not tested yet?

No. Colorado's online registration system will not process a renewal without a passing test result on file. You must complete the test first, then renew your registration either online or at a county clerk's office.

What if I just bought a used car and the previous owner did not get it tested?

You are responsible for testing before you renew the registration in your name. If the car is overdue for testing, you cannot legally register it until you pass. The test is the same as any other — the station does not care about the vehicle's history.

Do I have to test if I only drive my car a few months a year?

Yes, if your registration is active and the vehicle is subject to testing, you must test before renewal. If you do not plan to drive the car, you can let the registration expire instead of renewing it.

What if my vehicle is too old or damaged to pass?

If repairs are not economical, you can retire the vehicle through Colorado's scrappage program or sell it for parts. You cannot renew the registration without a passing test, so you cannot legally drive it on public roads.

Can I test in a different county than where I live?

Yes. You can test at any licensed station in Colorado, regardless of where you live or where you will register the vehicle. The test result is valid statewide.