What AA Smog Check Is and Who Needs It

AA Smog Check is California's vehicle emissions inspection program, run by the Bureau of Automotive Repair (BAR). It tests whether your vehicle's exhaust meets state pollution standards. Most vehicles registered in California need to pass a smog check every two years, though some newer cars and electric vehicles are exempt.

The "AA" refers to the test stations themselves — they are licensed by BAR and marked with an "AA" sign. You cannot get a smog check at a regular mechanic shop unless they hold a BAR license as an AA station. When you need to renew your vehicle registration, the California Department of Motor Vehicles (DMV) will not issue a new registration sticker without proof of a passing smog check (unless your vehicle is exempt).

The test takes about 30 minutes and costs between $30 and $70 depending on your vehicle type and the station. You pay the station directly — there is no state fee on top of that.

Key Takeaways

  • Most California vehicles need a smog check every two years before you can renew your registration with the DMV.
  • You must go to a BAR-licensed AA station; regular repair shops cannot perform the test unless they hold a BAR license.
  • The test checks your vehicle's exhaust emissions against California standards and takes about 30 minutes.
  • If your vehicle fails, you have 30 days to fix the problem and retest at no additional charge at the same station.
  • Newer vehicles (usually 2000 and newer) and electric vehicles may be exempt, but you should check your registration notice to be sure.

Finding an AA Smog Check Station Near You

The Bureau of Automotive Repair maintains an online search tool at smogcheck.ca.gov where you can enter your zip code and see all licensed AA stations in your area. The tool shows the station's address, phone number, hours, and whether they accept appointments or walk-ins.

Not all stations are the same. Some are independent repair shops that also perform smog checks; others are dedicated smog-check-only stations. Independent shops may be faster if you need repairs, but dedicated stations often have shorter wait times. Call ahead if you want an appointment — many stations will hold a time slot for you, which saves you from waiting.

Bring your vehicle's registration notice or renewal reminder when you go. The station will need your vehicle identification number (VIN), license plate number, and odometer reading. If your vehicle has been recently repaired, bring documentation of what was fixed — this helps the technician understand the vehicle's condition.

What Happens During the AA Smog Check Test

The technician will connect your vehicle to a dynamometer (a machine that measures emissions as your engine runs) or perform a visual inspection, depending on your vehicle's age and type. For most vehicles, the test involves driving on the dynamometer for a few minutes while the machine reads your exhaust gases.

The test measures three main pollutants: hydrocarbons (HC), carbon monoxide (CO), and nitrogen oxides (NOx). Your vehicle passes if all three fall below California's limits for your vehicle's model year. The limits are stricter for newer vehicles than older ones.

The station will print a test report showing whether you passed or failed. If you passed, they will provide a smog check certificate that you can take to the DMV or use to renew your registration online. The certificate is valid for 30 days, so you have that window to complete your registration renewal.

What to Do If Your Vehicle Fails the Smog Check

If your vehicle fails, you have 30 days to repair the problem and return to the same station for a retest at no charge. The test report will show which emissions are too high, which gives you and a mechanic a starting point for diagnosis.

Common reasons for failure include a faulty oxygen sensor, a loose or missing gas cap, a failing catalytic converter, or engine problems that trigger the check-engine light. Some repairs are straightforward and inexpensive (like replacing a gas cap); others are more involved. A mechanic can read your vehicle's diagnostic codes to narrow down the cause.

You do not have to repair the vehicle at the same station where you failed the test. You can take it to any mechanic you trust. Once repairs are done, return to the original AA station within 30 days for the retest. If you pass the retest, you receive a passing certificate and can renew your registration.

If you fail the retest, you have another 30 days to make further repairs and test again. After two failed retests, you may be required to visit a referee station (a BAR-operated facility) for a third opinion before you can register your vehicle.

Vehicles Exempt from AA Smog Check

Not every California vehicle needs a smog check. Electric vehicles (battery-electric and plug-in hybrids) are permanently exempt. Vehicles that are fewer than four model years old are exempt for their first registration; after that, they follow the standard two-year cycle.

Vehicles that are 1975 or older are also exempt. Some vehicles with recent major repairs may may have access to for a temporary exemption, though this is rare and requires BAR approval.

Your registration renewal notice will tell you whether your vehicle needs a smog check. If it does not say "smog check required," you do not need one. If you are unsure, call your local DMV office or check your registration documents.

Renewing Your Registration After Passing the Smog Check

Once you have a passing smog check certificate, you can renew your vehicle registration through the DMV. You can do this online at dmv.ca.gov, by mail, or in person at a DMV office. Online renewal is usually the fastest option.

If you renew online, you will need your registration renewal notice, your vehicle's VIN, and your smog check certificate number. The DMV will verify the certificate with the BAR system, so make sure the certificate number is correct. Registration renewal fees vary by vehicle type and county; check the DMV website for your specific cost.

Your new registration sticker will arrive by mail within a few weeks. Until it arrives, you can print a temporary registration document from the DMV website if you need proof of current registration.

What Happens If You Drive Without a Current Smog Check

If your registration has expired because you did not pass a smog check, driving your vehicle is illegal in California. You can be cited for expired registration, which carries a fine. The fine amount depends on how long your registration has been expired.

If you are pulled over, the officer will see that your registration is expired and that a smog check was required but not completed. You should get your vehicle tested and registered as soon as possible to avoid additional citations.

If your vehicle fails the smog check and you cannot afford repairs, some counties offer repair information programs through their air quality management districts. Contact your local air quality agency to ask whether a program is available in your area.

Frequently Asked Questions

Can I get a smog check before my registration expires?

Yes. You can get a smog check up to 90 days before your registration expires. The certificate is valid for 30 days, so if you test early, make sure you renew your registration within that 30-day window or you will need to test again.

What if I just bought a used car — do I need a smog check right away?

Only if the vehicle's registration has expired or is about to expire. If the seller transferred a current registration to you, you do not need a smog check until that registration comes due for renewal. Check your registration notice to see when your next smog check is required.

Can I use a smog check from another state?

No. California only accepts smog checks performed at BAR-licensed AA stations in California. If you moved to California from another state, you will need a California smog check before you can register your vehicle here.

What if the smog check station gave me the wrong certificate number?

Contact the station when ready and ask them to provide the correct certificate number. You will need the correct number to renew your registration. If the DMV cannot verify your certificate, your registration renewal will be delayed until the number is corrected.

Do I need a smog check if I am only renewing my registration by mail?

Yes, if your registration notice says a smog check is required. The DMV will not process your renewal without proof of a passing smog check, whether you renew by mail, online, or in person. Mail in your smog check certificate along with your renewal form and payment.