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.