Arizona requires emissions testing through ADEQ, and you must pass before you can register your vehicle
Arizona's Department of Environmental Quality (ADEQ) oversees the state's vehicle emissions program. If you live in Maricopa or Pima County — the two areas where testing is required — you must have your vehicle tested and pass before the Arizona Motor Vehicle Division will issue or renew your registration. The test checks whether your vehicle's exhaust meets state pollution standards.
ADEQ does not run the testing stations themselves. Instead, the department certifies private repair shops and testing facilities to perform the test. You choose where to go, pay the testing fee directly to that facility, and receive a pass or fail result on the spot. If you pass, the result uploads to ADEQ's system and the Motor Vehicle Division can see it when you renew your registration.
The requirement applies to most gasoline vehicles model year 1975 and newer in the two counties. Diesel vehicles, motorcycles, and vehicles under 10,000 pounds registered as commercial have different rules. New vehicles are exempt for their first four model years.
Key Takeaways
- ADEQ emissions testing is required only in Maricopa and Pima Counties, and you must pass before the Motor Vehicle Division will renew your registration.
- You choose a certified testing facility from ADEQ's list — the department does not operate the stations — and pay the facility's fee, which varies by location.
- The test takes about 10 to 15 minutes and checks whether your vehicle's exhaust meets state pollution standards; results are available when ready.
- If you fail, you have 60 days to repair your vehicle and retest at no additional charge at the same facility.
- Vehicles model year 1975 and newer are generally required; new vehicles are exempt for their first four model years, and some vehicle types have different rules.
Which Arizona counties require ADEQ testing
Only Maricopa County (which includes Phoenix) and Pima County (which includes Tucson) have mandatory emissions testing. If you register your vehicle in any other Arizona county, you do not need to pass an ADEQ test to renew your registration.
If you live in one of the two required counties but your vehicle is registered elsewhere, you will not be required to test. However, if you move to Maricopa or Pima County and register your vehicle there, the requirement begins with your next registration renewal.
How to find a certified testing facility
ADEQ maintains a searchable list of certified testing stations on its website. You can search by county and city to find facilities near you. The list includes repair shops, quick-lube centers, and dedicated emissions testing stations. Each facility sets its own testing fee, which typically ranges from $15 to $30, though prices vary.
You do not need an appointment at most facilities, but some accept them. Call ahead if you want to confirm hours or avoid a wait. Bring your vehicle keys and proof of vehicle ownership or registration. The test itself takes about 10 to 15 minutes.
What happens during the test and what results mean
The technician will connect your vehicle to a dynamometer or tailpipe analyzer, depending on the facility's equipment. For most vehicles, the test measures exhaust emissions while the engine runs at idle and at a simulated driving speed. The machine records whether your vehicle's nitrogen oxides, carbon monoxide, and hydrocarbon levels fall within state limits.
You receive a pass or fail result when ready. A pass means your vehicle meets Arizona's standards and you can proceed with registration renewal. A fail means your vehicle's emissions exceed the limit for one or more pollutants.
If you fail, you have 60 days to repair your vehicle and retest. The retest is free at the same facility where you failed. You do not pay again. After you pass the retest, the result uploads to ADEQ's system and you can complete your registration renewal.
Vehicle types and model years that are exempt or have different rules
New vehicles are exempt from testing for their first four model years. For example, a vehicle purchased in 2024 does not need to test until 2028. After that, it follows the standard requirement.
Diesel vehicles registered in Arizona are not required to test under the ADEQ program, though they may be subject to federal heavy-duty diesel standards if they are commercial vehicles. Motorcycles and vehicles registered as off-highway are also exempt. Vehicles under 10,000 pounds registered as commercial may have different requirements depending on their use.
If you are unsure whether your vehicle is exempt, check ADEQ's rules or ask the testing facility when you call. The Motor Vehicle Division will also tell you during registration renewal whether a test is required.
What to do if your vehicle fails the test
A failed test does not prevent you from driving your vehicle. It only prevents you from renewing your registration until you pass. You have 60 days from the test date to repair your vehicle and retest.
Common reasons for failure include a faulty oxygen sensor, a loose or damaged gas cap, a malfunctioning catalytic converter, or an engine that is running too rich. A repair shop can diagnose the problem using a code reader or by visual inspection. Some repairs are inexpensive (a gas cap may cost $10 to $20), while others (a catalytic converter) can cost several hundred dollars.
If repair costs are high and your vehicle is older, you may want to get a second opinion from another shop before proceeding. Once you repair the vehicle, return to the same testing facility for a free retest. You do not need to pay the testing fee again.
How ADEQ results connect to vehicle registration
When you pass an ADEQ test, the result is uploaded to ADEQ's database within one business day. The Arizona Motor Vehicle Division can see your pass result when you renew your registration online, by mail, or in person.
If you renew your registration before your test result appears in the system, your renewal may be delayed. If this happens, contact the Motor Vehicle Division with your test receipt or facility name and date. They can verify your pass result manually.
You do not need to bring your test receipt to the Motor Vehicle Division. The division checks ADEQ's system automatically. However, keep your receipt for your records in case there is a delay or a question about when you tested.
Frequently Asked Questions
Do I have to test at a specific facility or can I choose any certified station?
You can choose any certified facility on ADEQ's list. There is no requirement to use a particular shop or location. If you fail and want to retest, you must return to the same facility for the free retest, but you can choose a different facility for your initial test.
What if I move out of Maricopa or Pima County after I register my vehicle there?
Once you move and register your vehicle in a county without testing requirements, you will no longer need to pass an ADEQ test to renew. However, if you move back to Maricopa or Pima County and re-register there, the requirement applies again at your next renewal.
Can I test my vehicle before my registration expires?
Yes. You can test your vehicle up to 120 days before your registration expires. This allows you to repair and retest if needed while still having time to renew your registration before it expires. Testing early can help you avoid a lapsed registration.
What if the testing facility goes out of business after I fail?
You can retest at any other certified facility. You will need to pay the testing fee again at the new facility, but ADEQ will waive the fee if you bring your original fail receipt and test within 60 days. Contact ADEQ to confirm the waiver process before you visit the new facility.
Are there any vehicles that passed before but are now required to test?
No. Once a vehicle is exempt (such as a new vehicle in its first four years), it remains exempt during that period. The requirement only begins after the exemption period ends. After that, the vehicle must test every two years as part of the registration renewal cycle.