What should I do if my car fails the emissions test

If your vehicle has failed an emissions test at an Arizona facility, they’ll usually give you some indication about why it has failed. You can take that information and provide it to any mechanic and with any luck they will be able to make some repairs to your vehicle. You can take a free-retest after you complete your repairs.

Why do I need emissions test in Arizona? The reason is because Arizona is one of the fastest growing states in the country and because of the mountains surrounding our cities (especially Phoenix) air pollution tends to settle in the valleys. This creates a smog build up that is visible in the air. What happened was that the Motor Vehicle Division (MVD) partnered with the Arizona Department of Environmental Quality (ADEQ) to administer a program they dubbed Car Care. The program is designed to control emissions and reduce pollution in the air. Arizona risks losing millions of dollars in federal highway funds if they don’t participate in the Clean Air Act, a federal program.

There are 31 states that require vehicle-emissions testing. Of those, 9 operate like Arizona with locations centralized. Other states allow independent auto-repair shops to check emissions. One reason Arizona doesn’t allow independent auto-shops to test is because we have more stringent standards. Arizona tests older vehicles (1967 to 1995 models) on the dynamometer rolling system. This system is too expensive for most auto shops to install.

Data from 2011 shows that only 6.3% of 2006 model vehicles failed the initial emissions test. Older cars made between 1967 and 1977 had higher failure rates usually between 32-43% (that’s high!). Here’s a great article from The Arizona Republic about the emissions testing program.

More than 90% of newer vehicles pass the test on the first run (about 1.3 million Arizonans a year).

First, the good news! You’re car re-inspection is free (as long as you return within 60 days) and you complete the repair information notes (reverse side of the original vehicle inspection report).

If your vehicle fails the emissions test two or more times and you have made reasonable attempts to repair it, then you may qualify for a waiver.

Some common reasons for a smog check failure include:

HC – Hydrocarbon faults:

  • Incorrect ignition timing
  • Faulty spark plugs and/or wires
  • Lean fuel mixtures
  • Vacuum leaks
  • Low cylinder compression

CO – Carbon Monoxide faults:

  • Faulty oxygen sensor(s)
  • Defective MAP sensor
  • Defective TPS sensor
  • Defective ECT sensor
  • Faulty fuel injection/carburetor

NOx – Nitrous Oxide faults:

  • Defective EGR system
  • Lean fuel mixtures
  • Overheating engine
  • High cylinder compression
  • Defective catalytic converter

Note: The possibilities listed above vary based on your vehicles make and model. Some times a vehicle can fail based on something entirely different. Always do a hands on diagnosis and speak with a qualified mechanic.

If the check-engine light is on, you’ll most likely want to check that out with your mechanic prior to getting your emissions test done. The folks at ADEQ actually recommend getting a check-engine light looked at prior to testing since it is likely to fail.

Here is a wonderful article that provides an overview of what you can do to pass an emissions test if your car had previously failed.

Do I need to have my car emissions tested in Arizona?

You’ll want to check with the state, but you typically do not need to have your emissions tested if you:

  • Arizona does exempt most vehicles of the newest five model years
  • Vehicle is registered outside of the test area – typically outside of Phoenix or Tucson – in this case, use the ADEQ address locator.
  • Have a vehicle that is located outside of the State of Arizona.
  • If you are active duty military and stationed outside of Arizona and nobody else is using your vehicle you may apply for an exemption.
  • Vehicles out of state at test time (sometimes you need to get it tested in another state, or they will give you a 1-year exemption).
  • Information from the state about exemptions.

Emissions Testing Locations in Phoenix – Frequently asked questions

So, you’re looking for the best place to get your vehicle inspected for emissions? This little FAQ has been produced by a Phoenix resident who has done it before.

Q: What happens if my car fails?
A: You simply need to take your car to a mechanic, or fix it yourself, and then return for a complimentary test. In most cases, you can ask the attendant to explain why your car failed and they’ll be able to point you in the right direction. If you have to take a third test, you will be required to pay again.

Q: How long does it take?
A: Getting your car emissions tested usually takes less than 10 minutes, not including wait times. You can check webcams of locations online to get a sense for how many cars are ahead of you.

Q: How can I get the best result?
A: While waiting in line, if you leave your vehicle running it can heat up and cause a failure. Less from the heat, and more from the emissions build up due to lack of motion. We recommend revving the engine To avoid over-heating while waiting. Keep the engine running and, while in neutral or park, rev the engine for 15 seconds at a time. Turn off your air conditioner. This is the recommended practice.

Q: Cold engine or hot engine?
A: I have personally experienced taking a car that I just started over to the emissions testing facility… and failed. So, take my advice and drive around for 15 minutes to warm up your vehicle. It will run better and be more likely to pass.

Q: Can I bring a trailer?
A: No, leave your trailer at home.

Q: Can I bring a passenger?
A: They say no, but you can… you are even able to bring your child. The driver will be required to step out of the vehicle for a few minutes, however.

Q: My check engine light is on, will my car still pass?
A: ADEQ recommends that you have your vehicle inspected by a mechanic to determine the reason. They state that “1996 and newer vehicles with on-board diagnostic (OBD) equipment will not pass emissions testing if the check engine light is on.”

Do you have a question? If so, get in touch!

Scottsdale Emissions Testing Locations

The best location in Scottsdale is in the Scottsdale Airpark on Evans.

8448 E. Evans
Scottsdale, AZ 85260

This location has the same hours as the other locations, which are Monday – Friday from 8am – 7pm, and Saturday from 8am – 5pm.

Emission testing is often faster mid-week, and in the middle-of-the-month., as well as weekdays after work from 5-7pm. Believe it or not, you can also usually get in and out quickly on Saturday afternoons.

Closed: New Year’s Day, Memorial Day, July 4, Labor Day, Thanksgiving,
Christmas Eve and Christmas Day. Pretty much what you would expect.