ADEQ emissions testing stations are Arizona Department of Environmental Quality-certified facilities where you get your vehicle tested to meet state pollution standards

Arizona requires emissions testing for most vehicles registered in Maricopa, Pima, and Yavapai counties. The Arizona Department of Environmental Quality (ADEQ) oversees the program and certifies the stations that perform the tests. These are private businesses — repair shops, tire stores, and dedicated testing centers — that have met ADEQ's equipment and training standards. You cannot test at just any mechanic; the station must display an ADEQ certificate.

The test itself takes about 10 to 15 minutes and measures your vehicle's tailpipe emissions. The station plugs a probe into your vehicle's diagnostic port (or tailpipe on older vehicles) and records the results. You pay a fee that varies by station but is typically between $20 and $40. If your vehicle passes, you receive a certificate that you take to the Arizona Department of Motor Vehicles when you renew your registration. If it fails, you have 60 days to repair the vehicle and retest at no additional fee at the same station.

Key Takeaways

  • ADEQ-certified stations are the only places where Arizona emissions tests are valid; you can find them through the ADEQ website or by calling your county environmental office.
  • The test costs between $20 and $40 depending on the station, takes 10 to 15 minutes, and you need your vehicle registration and proof of insurance.
  • If you fail, you have 60 days to repair your vehicle and retest at the same station for free; the station must retest you without charging again.
  • Emissions testing is required in Maricopa, Pima, and Yavapai counties; vehicles in other Arizona counties do not need to test.

Finding an ADEQ-certified station near you

The ADEQ website maintains a searchable list of certified emissions testing stations organized by county. Go to azdeq.gov, navigate to the emissions testing section, and enter your county and city. The list shows the station name, address, phone number, and hours. Call ahead to confirm they are open and accepting vehicles, since some stations have limited hours or may be temporarily closed.

If you do not have internet access, call your county environmental office directly. Maricopa County residents can reach the Maricopa County Air Quality Department, Pima County residents can contact Pima County Department of Environmental Quality, and Yavapai County residents should call the Yavapai County Air Quality Division. They can tell you which stations are nearest and currently operating.

What to bring and what the test covers

Bring your vehicle registration and proof of insurance. The station will need your vehicle identification number (VIN) and current mileage. Your vehicle's engine should be warmed up before you arrive — a cold engine can fail the test even if the vehicle would pass when warm. If your check engine light is on, the vehicle will fail automatically; you must have the problem diagnosed and repaired before retesting.

The test measures nitrogen oxides, particulate matter, and other pollutants based on your vehicle's model year and type. Diesel vehicles and gasoline vehicles are tested differently. Vehicles older than 1975 are exempt from testing. Vehicles registered as classic cars or motorcycles may have different requirements; ask the station when you call.

What happens if you fail the emissions test

A failure means your vehicle's emissions exceed Arizona standards. The station will give you a written report showing which pollutants were too high. You then have 60 days to repair the vehicle and return to the same station for a retest. The retest is free — you do not pay the testing fee again. The station is required by ADEQ to retest you without charging.

Common reasons for failure include a faulty oxygen sensor, a clogged fuel injector, a bad catalytic converter, or an engine that is running too rich (burning too much fuel). A mechanic can diagnose the specific problem using the failure report. Some repairs are inexpensive; others cost several hundred dollars. If you cannot afford the repair, ask the station or your mechanic about ADEQ's vehicle repair information program, which may help cover costs in certain cases.

Retesting after a repair

Once you have repaired your vehicle, return to the same station where you failed. Bring your repair receipt or documentation showing what was fixed. The station will retest your vehicle at no charge. If you pass the retest, you receive a new certificate valid for two years (or one year for vehicles 1996 and older). If you fail again, you have another 60 days to repair and retest.

If you fail twice and cannot afford further repairs, ADEQ may place your vehicle on a waiver, which allows you to register it anyway. Waivers are not automatic; you must request one through ADEQ after the second failure. The waiver is valid for one year and costs a fee. Contact ADEQ directly to learn whether your vehicle qualifies.

Emissions testing requirements by county and vehicle age

Maricopa County (which includes Phoenix) requires testing for most vehicles. Pima County (Tucson) and Yavapai County (Prescott area) also require testing. If you live outside these three counties, your vehicle does not need an emissions test. Check your vehicle registration to see which county you are registered in.

Vehicles registered in the required counties must test unless they are exempt. Vehicles older than 1975 are exempt. Vehicles registered as classic cars, motorcycles, or trailers may be exempt; the station can tell you when you call. New vehicles (current model year) are often exempt for the first few years; check your registration or call ADEQ to confirm.

Timing your emissions test with vehicle registration renewal

You need a passing emissions certificate before you can renew your vehicle registration. Arizona sends renewal notices 60 days before your registration expires. Plan to test at least two weeks before your registration expires so you have time to repair and retest if needed. If you test and pass, take the certificate to the Arizona Department of Motor Vehicles in person, by mail, or through their website when you renew.

If your registration has already expired, you can still test and renew, but you may face a late fee. Do not drive a vehicle with an expired registration in Arizona; you can be cited. If you are unsure when your registration expires, check your registration card or log into your AZDMV account online.

Frequently Asked Questions

Can I test at any repair shop or does it have to be an ADEQ-certified station?

It must be an ADEQ-certified station. The station will display an ADEQ certificate in the window or office. Testing at an uncertified shop will not produce a valid certificate, and you will have to test again at a certified station. Use the ADEQ website list to confirm before you go.

What if I fail the test twice and cannot afford to repair my vehicle?

After a second failure, you can request a waiver from ADEQ that allows you to register your vehicle anyway for one year. You must request the waiver through ADEQ; the station cannot issue it. There is a fee for the waiver. Contact ADEQ directly to see if your vehicle qualifies and to learn the current waiver fee.

Do I have to retest at the same station where I failed, or can I go somewhere else?

You must retest at the same station where you failed. ADEQ requires this so the station can verify that repairs were actually made. If the original station has closed, contact ADEQ to find out where you can retest.

How long is an emissions certificate good for?

A passing certificate is valid for two years (one year for vehicles 1996 and older). You can renew your registration anytime during that two-year window. The certificate expires on the date printed on it, not on your registration expiration date.

What if my check engine light is on when I go to test?

Your vehicle will fail automatically if the check engine light is on. You must have the problem diagnosed and repaired before you can pass the test. Take your vehicle to a mechanic, have them read the diagnostic code, and fix the underlying problem. Once the light is off and the repair is complete, return to the station for a retest.