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

In California, a smog check (also called a smog test or emissions inspection) is required every two years for most passenger vehicles. The exact timing depends on when your vehicle was first registered in the state. If you registered your car in an odd-numbered year, your smog check is due in odd-numbered years. If you registered it in an even-numbered year, it's due in even-numbered years. You can get your smog check done any time during your registration year, but you must have a current one before you can renew your registration.

Some vehicles are exempt from smog checks entirely. New cars (typically those less than four model years old) do not need a smog check for their first registration. Diesel vehicles over 14,000 pounds, electric vehicles, and motorcycles registered as such are also exempt. If your vehicle is older than 1975 or was not originally designed to meet California emissions standards, it may be exempt as well. The California Department of Consumer Affairs maintains the official list of exempt vehicle types.

Key Takeaways

  • Most California vehicles need a smog check every two years, timed to your registration year (odd or even).
  • New vehicles under four model years old are exempt from smog checks for their first registration period.
  • You can take your smog check any time during your registration year, but you must have a passing result before renewing your registration.
  • If your vehicle fails, you have 30 days to repair it and retest at no additional cost at the same station.
  • Smog check stations are certified by the state and can be found through the Bureau of Automotive Repair website.

When your smog check is actually due

Your smog check due date is tied to your vehicle registration expiration date, not to the calendar year. When you register a vehicle in California, you receive a registration sticker that shows the month and year your registration expires. Your smog check must be completed before that expiration date arrives. Many people complete their smog check in the month before expiration to avoid a rush, but you can do it earlier in the year if you prefer.

If you let your registration expire without a current smog check, you cannot legally drive the vehicle on California roads. You will also face a fine if you are pulled over. To get back into compliance, you must obtain a smog check, pass it, and then renew your registration. Some smog check stations offer "out-of-compliance" testing for vehicles that have expired registrations, but this does not change the two-year cycle — your next smog check will still be due two years from your original registration date.

Vehicles that do not need smog checks

New vehicles are exempt for their first registration period. Specifically, if your vehicle is less than four model years old at the time of registration, you do not need a smog check. A 2024 vehicle registered in 2024 would be exempt. Once that four-year window closes, you will need a smog check at your next registration renewal.

Older vehicles may also be exempt. Vehicles manufactured before 1975 are not required to have smog checks. Some vehicles registered as motorcycles, motorized bicycles, or off-highway vehicles are exempt. Diesel vehicles over 14,000 pounds are exempt from the standard smog check program, though they may be subject to different heavy-duty diesel inspection requirements. Electric vehicles registered as such do not need smog checks because they produce no tailpipe emissions. If you are unsure whether your vehicle is exempt, the Bureau of Automotive Repair website has a searchable database.

What happens if your vehicle fails the smog check

If your vehicle fails the smog check, you have 30 days to repair the problem and retest at the same station at no additional charge. The smog check technician will provide you with a report showing which emissions systems failed. Common reasons for failure include a faulty oxygen sensor, a malfunctioning catalytic converter, or an illuminated check engine light. You do not have to use the same repair shop as the smog check station — you can take the vehicle to any mechanic you trust.

Once you have made repairs, return to the same smog check station and request a retest. If the vehicle passes on the second attempt, you receive a passing certificate and can proceed with registration renewal. If it fails again, you have another 30 days to repair and retest. If your vehicle fails twice and you cannot afford the repairs, California offers the Consumer information Program, which provides repair information for low-income vehicle owners. You must contact the program before your 30-day window closes.

Finding a certified smog check station

Smog checks must be performed at a station certified by the California Bureau of Automotive Repair. Not all repair shops are certified to perform smog checks, and not all smog check stations do full repairs. You can find a certified station by visiting the Bureau of Automotive Repair's online station locator or by searching "smog check near me" in your area. The locator shows the station's address, phone number, and hours of operation.

Smog check costs vary by station but typically range from $30 to $60 for a basic test. Some stations charge more if additional diagnostics are needed. You should call ahead to confirm the price and ask whether the station accepts your preferred payment method. If you are retesting after a repair, confirm that the station will waive the retest fee — this is required by law, but it is worth verifying when you schedule.

Smog checks for vehicles with recent repairs or modifications

If you have recently had emissions-related repairs done, you may need to clear the vehicle's diagnostic trouble codes before the smog check. Many repair shops do this automatically, but if you go to an independent mechanic, ask them to clear the codes and drive the vehicle for at least 100 miles before your smog check appointment. This allows the vehicle's onboard diagnostic system to relearn and verify that the repair was successful.

If you have modified your vehicle's engine, exhaust system, or fuel system, it may fail the smog check even if the original components would have passed. California emissions standards explore to the vehicle as it currently exists, not as it left the factory. Aftermarket parts must be California-certified to be legal. If you are considering modifications, check whether they are legal in California before installation — an illegal modification can result in a failed smog check and a citation.

Smog checks when buying or selling a vehicle

When you buy a used vehicle in California, the seller must provide a smog check certificate dated within 90 days of the sale. This is a requirement of the sale, not a separate inspection you arrange yourself. The seller is responsible for obtaining this certificate before the sale is complete. If the vehicle fails the smog check, the seller must either repair it or disclose the failure to you in writing before you purchase it.

If you are selling a vehicle, you are responsible for providing a passing smog check certificate to the buyer. You can obtain this certificate up to 90 days before the sale. If your vehicle fails, you must repair it and retest before the sale can proceed. Some private sellers arrange for the buyer to handle the smog check as part of the purchase agreement, but this must be agreed to in writing before the sale.

Frequently Asked Questions

Can I get a smog check more than two years early?

Yes, you can take your smog check any time during your registration year, even if it is months before your registration expires. However, the smog check certificate is only valid for 30 days before your registration expires. If you test too early, your certificate may expire before you can use it for registration renewal.

What if I move out of California but still own a California-registered vehicle?

If your vehicle is registered in California, it must have a current smog check to renew that registration, regardless of where you live. You can take the smog check in any California-certified station. If you move permanently out of California and want to register the vehicle in another state, you will need to follow that state's registration process instead.

Do I need a smog check if I only drive my vehicle occasionally?

Yes, the smog check requirement is based on your registration expiration date, not on how often you drive. If your registration is active, you must have a current smog check. If you do not plan to drive the vehicle, you can let your registration expire instead, which removes the smog check requirement until you register it again.

What is the difference between a smog check and a smog certification?

A smog check is the test itself. A smog certification (or smog certificate) is the document you receive if the vehicle passes. You need the certification to renew your registration. If your vehicle fails, you do not receive a certification until it passes a retest.

Can I renew my registration without a smog check?

No, you cannot renew your registration without a passing smog check certificate, unless your vehicle is exempt. If you attempt to renew without one, the California Department of Motor Vehicles will reject your renewal. You must obtain a passing smog check before your registration expires to avoid driving with an expired registration.