What you need to know about Aurora's emissions test

Aurora requires emissions testing as part of your vehicle registration renewal if your car is model year 1981 or newer. The test measures what comes out of your tailpipe—carbon monoxide, nitrogen oxides, and particulate matter—to make sure your vehicle meets Colorado air quality standards. You cannot renew your registration without a passing test result, and you must complete testing before your current registration expires.

The test itself takes about 10 to 15 minutes. A technician plugs a probe into your vehicle's diagnostic port (usually under the steering wheel) and runs your engine through a short cycle while the equipment reads the emissions data. If your vehicle passes, you get a certificate when ready. If it fails, you'll know what system needs repair before you can retest.

Key Takeaways

  • Aurora emissions testing is required every two years for most vehicles, and you must pass before renewing your registration.
  • The test costs between $20 and $30 at any Colorado Department of Revenue-certified testing station in Aurora.
  • Vehicles model year 1981 and newer must be tested; diesel vehicles and those under 8,500 pounds have different requirements than larger trucks.
  • If your vehicle fails, you have 60 days to repair it and retest at no additional cost at the same station.
  • You can find certified testing stations through the Colorado Department of Revenue website or by searching "emissions testing Aurora CO" for locations near you.

Where to get tested in Aurora

Aurora has multiple Colorado Department of Revenue-certified emissions testing stations. These are independent businesses—repair shops, tire shops, and dedicated testing centers—that have been trained and certified to run the official test. You can find a current list on the Colorado Department of Revenue's website under "Emissions Testing Stations," which shows locations by county and city.

Call ahead before you go. Testing stations have different hours, and some are busier than others depending on the time of year. Many stations are open early morning and evening to accommodate people before or after work. Bring your vehicle registration or proof of ownership and a valid ID.

What happens if your vehicle fails

A failure means one or more emissions systems is not working correctly—usually the catalytic converter, oxygen sensors, or fuel system. The test report will tell you which system failed and by how much. You do not have to repair the vehicle at the testing station; you can take it to any mechanic you trust.

Once you repair the problem, you have 60 days to return to the same testing station for a retest at no charge. If you retest at a different station, you may be charged the full testing fee again. Keep your failure report and bring it with you when you return so the technician knows what was repaired.

Vehicles that are exempt or have different rules

Diesel vehicles registered in Colorado are not required to take the standard tailpipe test, though they may be subject to other inspection requirements. Vehicles that are model year 1980 or older are also exempt. Motorcycles and vehicles registered as antiques or classics have different rules depending on their age and use.

If you own a vehicle over 8,500 pounds (most full-size pickup trucks), it may fall under a different testing category. Check your registration paperwork or call the Colorado Department of Revenue to confirm whether your specific vehicle is required to test.

Timing and registration renewal

Your emissions test is valid for two years from the date you pass. You must have a passing test result before you can renew your vehicle registration online, by mail, or in person at an Aurora county office. If your registration expires before you get tested, you cannot legally drive the vehicle.

Plan to test about two weeks before your registration expires. This gives you time to get tested and, if needed, repair and retest without rushing. If you wait until the last few days and your vehicle fails, you may not have time to fix it and retest before your registration important date.

Cost and what to bring

Emissions testing in Aurora costs between $20 and $30 per test, depending on the station. This is a one-time fee per test; if you fail and need to retest, the retest at the same station is free within 60 days. Bring your vehicle registration or proof of ownership and a valid photo ID. Some stations may ask for your vehicle identification number (VIN) to look up your vehicle's history.

Payment methods vary by station—some take cash only, others accept cards. Call ahead if you want to confirm what they accept.

Common reasons vehicles fail emissions testing

The most common failure is a faulty oxygen sensor, which tells your engine how much fuel to burn. A failing catalytic converter is the second most common reason; this part filters harmful gases before they leave the tailpipe and is expensive to replace. A loose or missing gas cap can also trigger a failure because it allows fuel vapors to escape.

Other failures come from a malfunctioning fuel injector, a bad spark plug, or problems with the evaporative emissions system (which captures fuel vapors from the tank). Many of these repairs cost $100 to $500; a catalytic converter replacement can cost $800 to $2,000 depending on your vehicle. If your vehicle is old and has failed before, consider whether the repair cost makes sense compared to the vehicle's value.

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 test result is valid for two years, so if you test early, your new two-year window starts from that test date, not from your registration renewal date.

What if I buy a used car in Aurora—do I need to test it right away?

Not when ready, but you must have a passing test before you can register it in Colorado. If the vehicle came from out of state, you'll need to test it as part of the registration process. If it was already registered in Colorado, check the registration paperwork to see when the last test was done.

Can I test at a station outside Aurora?

Yes. Any Colorado Department of Revenue-certified station in the state can test your vehicle. The test is the same statewide. However, if your vehicle fails, you have 60 days to retest at the same station where it failed, so choose a location convenient to you.

What if my vehicle's check engine light is on?

Many vehicles with the check engine light on will fail emissions testing. Some testing stations can read your diagnostic codes before the official test to give you an idea of what might be wrong. If you know the light is on, consider having a mechanic diagnose it before you pay for the test.

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

Most Aurora testing stations accept walk-ins, but some require appointments, especially during busy seasons like the month before registration important date. Call ahead to confirm their process and wait times.