What you need to know about Aurora's emissions test

Aurora requires an emissions test every two years for most vehicles, and you can get one at any Colorado-certified testing station in or near the city. The test checks whether your vehicle's exhaust meets state pollution standards — it takes about 10 minutes and costs between $20 and $35 depending on the station. You'll need your vehicle registration and proof of insurance, and your car must be in running condition with no warning lights on the dashboard.

The test itself is straightforward: a technician plugs a diagnostic scanner into your vehicle's onboard computer port (located under the steering wheel on most cars made after 1996) and reads the emissions data. For older vehicles, the technician may perform a tailpipe test instead. If your vehicle passes, you get a certificate that's valid for two years. If it fails, you have 30 days to fix the problem and retest at no additional charge.

Key Takeaways

  • Aurora requires emissions testing every two years for vehicles registered in the city, with some exceptions for new cars and certain vehicle types.
  • You can visit any Colorado-certified testing station; the test takes about 10 minutes and costs $20 to $35.
  • Bring your vehicle registration and proof of insurance, and make sure your car runs without dashboard warning lights.
  • If you fail, you have 30 days to repair the problem and retest for free at the same station.
  • A passing certificate is valid for two years and satisfies Colorado's emissions requirement.

When Aurora requires an emissions test

You need an emissions test every two years if your vehicle is registered in Aurora and is subject to Colorado's emissions program. This applies to most gasoline-powered cars, trucks, and SUVs model year 1975 and newer. Diesel vehicles have different testing requirements and may need a separate test depending on their model year and weight.

New vehicles (current model year and one year prior) are exempt from testing for their first four years of registration. Vehicles registered outside Aurora but driven in the city do not need an Aurora-specific test — they follow the rules of their home county. When you renew your vehicle registration with the Colorado Department of Revenue, you'll need proof of a passing emissions test if your vehicle is due.

Finding a testing station in Aurora

Colorado maintains a list of certified emissions testing stations on the Colorado Department of Public Health and Environment (CDPHE) website. You can search by city or ZIP code to find stations near you in Aurora. Most stations are independent repair shops, tire shops, or dedicated testing facilities, and many offer same-day testing without an appointment.

Call ahead if you want to confirm hours or avoid a wait, but walk-in testing is common. Some stations are busier during the last week of your registration month, so testing earlier in the cycle can mean shorter waits. Prices are set by each station within state limits, so calling two or three nearby locations can save you a few dollars.

What happens during the test

The technician will ask for your registration and proof of insurance, then move your vehicle into the testing bay. For vehicles made after 1996, they'll locate the diagnostic port under the steering wheel, plug in a scanner, and read the emissions data stored in your vehicle's computer. This takes about five minutes. The scanner checks whether your vehicle's emissions control system is working and whether any fault codes are present.

For vehicles made before 1996, the technician performs a tailpipe test instead, inserting a probe into the exhaust pipe to measure carbon monoxide and hydrocarbons directly. Either way, the test is non-invasive and does not require any part of your vehicle to be disassembled. You'll have your results within 10 minutes.

Passing the test

Your vehicle passes if the emissions data falls within Colorado's limits and no fault codes are present on the diagnostic scan. A passing test means your vehicle's catalytic converter, oxygen sensors, and emissions control system are functioning properly. You'll receive a certificate that you can print or have emailed to you, and this certificate is valid for two years.

You do not need to carry the physical certificate with you — Colorado's registration system is linked to the testing database, and law enforcement can verify your test status electronically. However, keeping a copy at home is useful if you need to prove compliance to a lender or insurance company.

What to do if your vehicle fails

If your vehicle fails, the technician will give you a report showing which emissions standards were not met and what fault codes were detected. Common failure reasons include a faulty oxygen sensor, a loose or missing gas cap, a malfunctioning catalytic converter, or an active check engine light. The report will not tell you exactly how to fix the problem — that requires a mechanic's diagnosis — but it will point you toward the system that needs attention.

You have 30 days from the test date to repair your vehicle and retest at the same station at no charge. If you retest within 30 days and pass, the original failure is cleared from your record. If you cannot repair the vehicle within 30 days, you can request a waiver from the Colorado Department of Revenue, though waivers are granted only in specific circumstances such as major repairs that are delayed by parts availability.

Common reasons for test failures and what they mean

A check engine light is the most common reason for failure — it means your vehicle's onboard diagnostic system has detected a problem in the emissions control system. This could be a faulty oxygen sensor (often $150 to $300 to replace), a loose gas cap (free to tighten), or a failing catalytic converter (often $500 to $1,500 to replace). The technician's report will show the fault code, which you can take to a mechanic for diagnosis.

High emissions readings without a check engine light usually indicate a worn catalytic converter or a fuel system problem. A mechanic can perform a more detailed scan to pinpoint the issue. Some repairs are inexpensive (a fuel system cleaning may cost $100 to $200), while others are more costly. However, addressing emissions problems early often prevents more expensive engine damage later, so repairing a failed vehicle is usually worth the cost.

Frequently Asked Questions

Can I test my vehicle before my registration expires?

Yes. You can test up to 60 days before your registration expires, and the certificate will be valid for two years from the test date. Testing early gives you time to repair and retest if needed before your registration renewal important date.

What if I just bought a used car in Aurora?

If the vehicle is new to you, check the registration documents to see when the last test was performed. If it was more than two years ago, you'll need a test before you can renew registration. If it was within two years, the previous owner's test certificate carries over to you.

Do I need emissions testing if I have a hybrid or electric vehicle?

Hybrid vehicles that have a gasoline engine are subject to testing. Fully electric vehicles are exempt from emissions testing in Colorado. Check your vehicle's registration to confirm its fuel type if you are unsure.

What if my vehicle has a check engine light but I do not know why?

You can still take it for an emissions test — the technician will scan it and the report will show the fault code. Take that code to a mechanic, who can diagnose the specific problem. You do not need to fix it before testing; the test result will show whether it causes an emissions failure.

Can I test in a different Colorado city if I live in Aurora?

Yes. Any Colorado-certified testing station will test your vehicle regardless of where you live, as long as your vehicle is registered in Colorado. The test result is valid for registration renewal in Aurora.