California requires a smog check every two years for most vehicles, with some exceptions based on age and type

In California, you need a smog check every two years if your vehicle is model year 1976 or newer. The test must happen within 90 days before your registration expires. If your registration expires on June 15, you can get tested as early as March 16 that year.

Vehicles model year 1975 and older are exempt from smog testing. Diesel vehicles registered after January 1, 2000 also need testing, though the frequency and requirements differ slightly from gasoline vehicles. Electric vehicles and hydrogen fuel cell vehicles are permanently exempt.

If you buy a used vehicle in California, you do not need a smog check to register it — the seller's responsibility ends when they sell it. However, you will need one for your first renewal after purchase.

Key Takeaways

  • Most California vehicles need a smog check every two years, timed to expire within 90 days before your registration renewal date.
  • Vehicles from 1975 and older, electric vehicles, and hydrogen fuel cell vehicles do not need smog checks at all.
  • You can get tested up to 90 days early, so plan ahead rather than waiting until your registration is about to expire.
  • If you fail a smog check, you have 30 days to fix the vehicle and retest at no additional cost at the same station.

When your vehicle is exempt from smog testing

Vehicles registered before 1976 never need a smog check in California, regardless of how often you renew your registration. If you own a classic or antique car, you can skip this requirement entirely — though you may need a different registration type depending on how often you drive it.

Electric vehicles (EVs) and hydrogen fuel cell vehicles are permanently exempt. Motorcycles, motorhomes, and trailers also do not require smog checks. If you are unsure whether your vehicle type is exempt, the California Department of Consumer Affairs maintains a list on its Bureau of Automotive Repair website.

Vehicles that fail smog testing can sometimes may have access to for a Gross Polluter Abatement Program waiver, which exempts them from future tests if repairs would cost more than a set amount. This is not automatic — you must request it after a failed test and meet specific income and vehicle value thresholds.

How to schedule and prepare for your smog check

You can get a smog check at any Bureau of Automotive Repair (BAR) certified smog station. These are independent repair shops, dealerships, and chain service centers — not all repair shops are certified, so confirm the station's certification before you go. You can search for certified stations on the BAR website by zip code.

Bring your vehicle registration and a valid ID. The test itself takes 10 to 30 minutes and costs between $30 and $80 depending on the station and vehicle type. Prices are set by individual stations, so you can call ahead to compare. The test checks your vehicle's emissions through the onboard diagnostic system and a tailpipe test.

Before testing, make sure your check engine light is off. If it is on, the vehicle will fail automatically. A short drive at highway speeds sometimes clears temporary codes, but if the light stays on, you need repairs first. Do not attempt to clear the code yourself — the station will detect it.

What happens if you fail your smog check

If your vehicle fails, you have 30 days to repair it and return to the same station for a retest at no additional charge. The station must give you a written report listing the specific emissions systems that failed. Take this report to a repair shop — it tells the mechanic exactly what to fix.

Common failure reasons include a faulty oxygen sensor, a loose gas cap, a failing catalytic converter, or an engine control module problem. Many of these repairs cost between $100 and $500, though catalytic converter replacement can be significantly more. Some repair shops offer payment plans if the cost is high.

If you cannot afford repairs, ask the smog station whether you may have access to for the Gross Polluter Abatement Program. You must meet income limits and the vehicle must have a market value below a certain threshold. If you may have access to, the program waives future smog checks, though you still cannot register the vehicle until you either repair it or receive the waiver in writing.

Timing your smog check with registration renewal

California sends registration renewal notices 60 days before your registration expires. Your smog check must be completed within 90 days before that expiration date. This means you have a 30-day window before the 60-day notice arrives where you can test early without wasting time.

Plan to test in the month your registration expires, or up to two months before. Testing too early — more than 90 days before expiration — means your results will not be valid for registration, and you will need to test again. The smog station will not let you test if your registration is already expired.

If your registration expires and you have not tested, you cannot legally drive the vehicle until you get a smog check and renew your registration. Driving with an expired registration carries a fine, so do not delay once you receive your renewal notice.

Diesel vehicles and special testing requirements

Diesel vehicles registered in California after January 1, 2000 need smog checks every two years, the same frequency as gasoline vehicles. However, the test procedure is different — diesel vehicles use a different emissions standard and testing protocol.

Not all smog stations test diesel vehicles, so confirm before you go. Diesel testing may cost slightly more than gasoline testing. The same 90-day window before registration expiration applies, and the same 30-day retest window applies if you fail.

Older diesel vehicles (1999 and earlier) are exempt from smog testing in most cases, though some may be subject to the Diesel Particulate Matter Retrofit Program if they are used commercially. Check the BAR website or call your local smog station if you own a diesel vehicle from the 1990s or earlier.

What to do if you move out of California or sell your vehicle

If you move out of California, you do not need a smog check for your final registration renewal in the state. However, if you plan to register the vehicle in another state, that state may have its own emissions testing requirements — check with your new state's motor vehicle department.

When you sell a vehicle in California, the seller is responsible for providing a smog check report to the buyer. The buyer does not need a smog check to register the vehicle in their name, but they will need one at their first renewal. If you are buying a used vehicle, ask the seller for the smog report as proof the vehicle passed — this does not exempt you from future testing, but it confirms the vehicle was in compliance when you bought it.

Frequently Asked Questions

Can I get a smog check more than 90 days before my registration expires?

No. If you test more than 90 days early, your results will not be valid for registration renewal. You will need to test again within the 90-day window. Plan to test in the month your registration expires or up to two months before.

What if I fail my smog check and cannot afford repairs?

You may may have access to for the Gross Polluter Abatement Program, which waives future smog checks if your income and vehicle value meet the program's limits. Ask the smog station for details after a failed test. You still cannot register the vehicle until you repair it or receive the waiver in writing.

Do I need a smog check if I buy a used car from a private seller?

Not to register it initially — the seller's smog check responsibility ends at the sale. However, you will need a smog check at your first registration renewal after purchase. Ask the seller for their smog report as proof the vehicle was compliant when you bought it.

Are electric vehicles and hybrids exempt from smog checks?

Electric vehicles are permanently exempt. Hybrid vehicles (gas and electric) are not exempt — they need smog checks every two years like gasoline vehicles. Only pure electric and hydrogen fuel cell vehicles are exempt.

What happens if my registration expires before I get a smog check?

You cannot legally drive the vehicle. Get a smog check when ready and renew your registration. Driving with an expired registration results in a fine. The smog station will not test a vehicle with an already-expired registration, so renew first if needed.