What Arizona requires for emissions testing

Arizona requires emissions testing for most vehicles registered in Maricopa and Pima counties — the state's two most populated areas. Vehicles in these counties must pass a test every two years, or every year if the vehicle is model year 1975 or newer and fails the initial test. The test measures tailpipe emissions to may support your vehicle meets state air quality standards.

Outside Maricopa and Pima counties, Arizona has no statewide emissions testing requirement. However, if you move a vehicle into one of these counties or register it there, you will need to pass a test before or shortly after registration. The Arizona Department of Environmental Quality (ADEQ) oversees the program and sets the standards; testing itself is performed by private facilities certified by the state.

Your vehicle's registration renewal notice will tell you whether testing is required. If you live in a county that requires it, you cannot renew your registration without proof of a passing test result.

Key Takeaways

  • Only Maricopa and Pima counties in Arizona require emissions testing; most of the state does not.
  • Testing is required every two years for most vehicles, or annually if your vehicle failed a previous test.
  • You must pass the test before you can renew your vehicle registration in those counties.
  • Testing facilities are private businesses certified by ADEQ, and you can choose which one to visit.
  • The test typically costs between $20 and $40 per vehicle, depending on the facility.

Which Arizona counties require testing and which do not

Maricopa County, which includes Phoenix, requires emissions testing for all registered vehicles except motorcycles and vehicles over 25 years old. Pima County, which includes Tucson, has the same requirement. These two counties account for roughly two-thirds of Arizona's population and are designated as nonattainment areas under the Clean Air Act — meaning their air quality does not consistently meet federal standards.

All other Arizona counties — Coconino, Gila, Graham, Greenlee, La Paz, Mohave, Navajo, Santa Cruz, Yavapai, and Yuma — have no emissions testing requirement. If you register a vehicle in one of these counties, you do not need to pass a test to renew your registration, even if you previously lived in Maricopa or Pima.

If you move from a non-testing county into Maricopa or Pima, or if you buy a vehicle registered elsewhere and bring it into one of these counties, you will need to pass a test as part of the registration process. ADEQ's website lists all certified testing locations by county.

How the testing process works in Arizona

Arizona uses a two-tier testing system. Most vehicles take the Inspection and Maintenance (I/M) 240 test, which measures emissions while the vehicle runs on a dynamometer — a machine that simulates driving. The test lasts about 10 minutes and checks nitrogen oxides, carbon monoxide, and hydrocarbons. Vehicles model year 1981 and older, and diesel vehicles, may be exempt or subject to different testing.

You drive to a certified testing facility, provide your vehicle keys and registration, and wait while the technician runs the test. If your vehicle passes, you receive a passing certificate when ready, usually printed on the spot. If it fails, the certificate will show which emissions exceeded the standard. You can then take your vehicle to a repair shop, have the problem fixed, and return to any certified facility for a retest.

The entire process at the facility typically takes 15 to 30 minutes. Testing costs vary by facility but generally range from $20 to $40. You can visit any ADEQ-certified facility in your county; you do not have to return to the same one for a retest.

Finding a testing facility and scheduling in Arizona

ADEQ maintains a searchable list of certified testing facilities on its website, organized by county. You can search by city or zip code to find locations near you. Most facilities operate on a walk-in basis, meaning you can arrive without an appointment, though some accept reservations. Hours vary — many are open early morning and evening to accommodate working drivers, and some operate on weekends.

Call ahead if you want to confirm hours or ask about wait times. Some facilities are busier than others, particularly near the end of the testing cycle or close to registration renewal important date. If you fail a test and need a retest, you can visit any certified facility; you are not required to return to the same one.

Your registration renewal notice will show your test expiration date. Testing must be completed before that date to renew your registration. If your test expires and you have not renewed, you cannot legally drive the vehicle in Arizona until you pass a new test and renew your registration.

What happens if your vehicle fails the emissions test

A failing test result shows which emissions exceeded the standard — typically carbon monoxide, nitrogen oxides, or hydrocarbons. The certificate will list the specific pollutant and the measured level. This information helps a repair technician diagnose the problem. Common causes include a faulty oxygen sensor, a clogged air filter, worn spark plugs, or a malfunctioning catalytic converter.

After repair, you can return to any certified facility for a retest. There is no waiting period between a failed test and a retest, so you can test again the same day if repairs are completed quickly. If you fail a second time, you may be may be able to access for a repair information program, though availability and income limits vary. Contact ADEQ directly for current information about repair information.

If your vehicle fails and you cannot afford repairs, some nonprofits and community programs in Maricopa and Pima counties offer low-cost or free repair services. ADEQ's website lists these programs by county. You can also ask the testing facility for referrals to affordable repair shops.

Vehicles exempt from Arizona emissions testing

Motorcycles are exempt from emissions testing in both Maricopa and Pima counties. Vehicles manufactured before 1975 are also exempt, as are vehicles over 25 years old. Diesel-powered vehicles have different testing requirements than gasoline vehicles and may be subject to a visual inspection instead of the dynamometer test, depending on model year.

Electric vehicles and hybrid vehicles are subject to the same testing requirements as gasoline vehicles in Arizona, despite producing lower emissions. If your vehicle is electric or hybrid and registered in Maricopa or Pima County, you will still need to pass the I/M 240 test or the applicable alternative test for your vehicle type.

If you believe your vehicle should be exempt, check the ADEQ website or call the program office to confirm. Exemption rules can change, and some exemptions depend on specific model year or vehicle classification.

Costs and timing for Arizona emissions testing

Testing costs between $20 and $40 per vehicle at most certified facilities. Some facilities charge a flat rate; others charge more for certain vehicle types or if additional testing is needed. The cost is paid directly to the testing facility, not to ADEQ or the state.

Testing typically takes 15 to 30 minutes from arrival to completion. If you fail and need repairs, the time to retest depends on how quickly you can get your vehicle repaired. Some repair shops can diagnose and fix common emissions problems in a few hours; others may need a day or more. Once repairs are done, you can retest at any facility without waiting.

Your registration renewal notice will show your test expiration date. Plan to test at least a week before that date to allow time for repairs if needed. If you test close to the important date and fail, you may not have time to repair and retest before your registration expires.

Frequently Asked Questions

Do I need emissions testing if I just bought a used car in Arizona?

If you register the vehicle in Maricopa or Pima County, yes — you will need to pass a test before or as part of the registration process. If you register it in another Arizona county, no. Check your county's requirements before completing the purchase or registration transfer.

What if I move out of Maricopa or Pima County?

Once you register your vehicle in a county that does not require testing, you no longer need to pass emissions tests for that vehicle. However, if you move back into Maricopa or Pima County later, you will need to pass a test again to register there.

Can I renew my vehicle registration without a passing emissions test?

No. In Maricopa and Pima counties, you cannot renew your registration without proof of a passing test result. If your test expires before you renew, you must pass a new test first. Driving with an expired registration is illegal.

What if my vehicle is too old or too new for standard testing?

Vehicles manufactured before 1975 and vehicles over 25 years old are exempt. Newer vehicles and diesel vehicles may have different testing requirements. Contact ADEQ or a certified facility to confirm what applies to your specific vehicle.

How long does a passing emissions certificate last?

A passing certificate is valid for two years from the test date in both Maricopa and Pima counties. Your registration renewal notice will show your expiration date. You must pass a new test before that date to renew your registration.