What California's smog law requires

California's smog law requires most vehicles to pass an emissions test every two years (or annually for vehicles older than 1975). The state calls this the Smog Check program. Your car must meet tailpipe emission standards set by the California Air Resources Board, or CARB. If your vehicle fails, you cannot renew your registration until you repair it and pass a retest.

The law applies to all gasoline-powered vehicles registered in California, with a few exceptions. Vehicles that are brand new (current model year), motorcycles, and vehicles that have not been driven in California for more than six months are exempt. Diesel vehicles have different testing rules and thresholds.

You do not choose whether to test — the state requires it as a condition of registration. You do choose where to test: any Bureau of Automotive Repair (BAR) certified smog station can perform the test. The test itself costs between $30 and $50 at most stations, though prices vary.

Key Takeaways

  • California requires a smog test every two years for most vehicles, and you cannot renew your registration without a passing result.
  • You can take your vehicle to any Bureau of Automotive Repair certified smog station, and the test typically costs $30 to $50.
  • If your vehicle fails, you have 30 days to repair it and retest at no additional charge at the same station.
  • Vehicles from the current model year, motorcycles, and some other categories are exempt from smog testing.
  • The state uses smog test results to track which vehicles and manufacturers are meeting emission standards.

When your smog test is due

Your smog test is due every two years from the date you last passed one. The state sends you a renewal notice in the mail about 60 days before your registration expires, and that notice will tell you whether a smog test is required. If your registration expires and you have not tested, you cannot legally renew it.

Some vehicles are tested annually instead of every two years. These include all vehicles from 1975 and older, and any vehicle that failed its previous smog test. Once an older vehicle passes a test, it goes back to the two-year cycle.

You can test up to 60 days before your registration expires. Testing early does not extend your registration — your registration renewal date stays the same — but it lets you know whether repairs are needed and gives you time to complete them.

What happens if your vehicle fails

If your vehicle fails the smog test, the station gives you a written report showing which emission standards it did not meet. You then have 30 days to repair the vehicle and bring it back to the same station for a free retest. You do not pay for the retest itself, though you pay for any repairs the vehicle needs.

If the vehicle still fails after repairs, you have another 30 days and another free retest. This cycle can continue, but most repairs are completed within the first 30 days. If you cannot afford repairs, some counties offer Smog Abatement and Retrofit (SMAR) programs that help pay for emission-related repairs on older vehicles.

If you do not retest within 30 days, the test result expires and you must start over with a new test. You cannot renew your registration until you have a passing test result on file.

Finding a certified smog station

Any station certified by the Bureau of Automotive Repair can perform a smog test. You can search for certified stations on the BAR website by entering your zip code. The search shows you the station's address, phone number, and hours. Most independent repair shops, dealerships, and chain automotive stores have certified technicians.

Prices are not regulated, so you can call ahead and ask what the test costs. Most stations charge between $30 and $50. Some stations offer package deals if you need repairs in addition to testing, but you are not required to have repairs done at the same place where you test.

When you go to test, bring your vehicle registration and a photo ID. The test takes about 10 to 15 minutes. The technician will connect your vehicle to a machine that measures what comes out of your tailpipe and compares it to California's standards for your vehicle's model year and engine type.

Vehicles exempt from smog testing

Not all registered vehicles need smog tests. The following are exempt: any vehicle from the current model year (brand new), all motorcycles, vehicles with a Planned Non-Operation status, and vehicles registered as classic cars or street rods under specific conditions. Diesel vehicles are tested, but they use different standards and equipment than gasoline vehicles.

Vehicles that have not been driven in California for more than six months are also exempt. If you move out of state and then move back, you may not need a test for your first registration renewal, depending on how long you were gone. Ask the Department of Motor Vehicles when you renew.

Electric vehicles are exempt from smog testing because they produce no tailpipe emissions. Hybrid vehicles that still have a gasoline engine are not exempt and must pass the test.

What to do if you cannot pass the test

If your vehicle repeatedly fails the smog test even after repairs, you have a few options. First, make sure the repairs being done are actually emission-related. Some shops may recommend expensive repairs that are not required by the smog test. Ask the technician to show you exactly which emission standard the vehicle is not meeting.

Second, get a second opinion. You can take your vehicle to a different certified station and have them diagnose the problem. This costs another test fee, but it may reveal a different issue or a less expensive repair path.

Third, look into your county's Smog Abatement and Retrofit program if you own an older vehicle. These programs can pay for repairs or, in some cases, help you replace an older vehicle with a newer one. Contact your local air quality management district to see what programs are available in your area.

If your vehicle cannot be repaired to pass the test, you may be able to register it under a Planned Non-Operation status, which exempts it from smog testing. This is meant for vehicles that are not driven regularly. You must declare the vehicle non-operational with the DMV.

How smog test results are used

Your individual smog test result is recorded in the state's database and used to track whether your vehicle meets California's emission standards. The state does not use your test to fine you or penalize you beyond requiring repairs — the test is a gate to registration, not a punishment.

Collectively, smog test results help California monitor which vehicles and manufacturers are meeting standards. If a particular model year or manufacturer shows a pattern of failures, CARB may investigate and require recalls or design changes. The data also helps the state decide which vehicles need annual testing instead of biennial testing.

Your test result is also used if you ever sell your vehicle in California. The buyer will see the test history when they check the vehicle's registration record, which can affect the vehicle's value and their ability to register it.

Frequently Asked Questions

Can I test my vehicle before my registration expires?

Yes, you can test up to 60 days before your registration expires. Testing early does not change your registration renewal date, but it gives you time to make repairs if needed. If you test and pass, the result is valid for two years from the date of the test.

What if I move out of California?

Once you register your vehicle in another state, you no longer need California smog tests. If you move back to California later, your new registration will require a smog test unless you may have access to for an exemption based on how long you were out of state.

Do I have to repair my vehicle at the smog station where I tested?

No. You can take your vehicle to any repair shop you choose. The smog station only tests; it does not have to do the repairs. You can get a second opinion on what repairs are needed before you pay for anything.

What if the smog station made a mistake on my test?

You can request a retest at a different certified station. If you believe the equipment was faulty or the test was performed incorrectly, contact the Bureau of Automotive Repair and file a complaint. You may also request an official review of your test results through the BAR.

Are hybrid vehicles required to take the smog test?

Yes, hybrid vehicles with gasoline engines must pass the smog test. Only fully electric vehicles are exempt. The test measures emissions from the gasoline engine, just as it does for any other gas-powered vehicle.