California's smog check schedule depends on your vehicle's age and type

Most California vehicles need a smog check every two years. The exact timing depends on when your car was first registered in California and whether it's a gasoline or diesel vehicle. New cars registered after January 1, 2000 don't need their first smog check until eight years after registration, then every two years after that. Older gasoline vehicles registered before 2000 need a check every two years from the date of their last passing test.

Diesel vehicles follow a different schedule. Heavy-duty diesel trucks and buses may need checks annually or every two years depending on their weight and model year. Light-duty diesel vehicles registered after January 1, 2000 follow the same eight-year-then-every-two-years pattern as gasoline cars. If you're unsure which category your vehicle falls into, the California Department of Consumer Affairs website has a lookup tool, or your smog technician can tell you when you arrive for testing.

Key Takeaways

  • Most California vehicles need a smog check every two years, but new cars get an eight-year grace period before their first test.
  • Your smog check is due two years from the date you last passed, not from the calendar year, so the timing is specific to your vehicle's history.
  • You cannot renew your vehicle registration without a passing smog check if your vehicle is due, and the Department of Motor Vehicles will flag your renewal as incomplete.
  • Certain vehicles are exempt from smog checks, including electric vehicles, motorcycles, and vehicles over 40 years old, but you must confirm your vehicle qualifies before skipping a test.

When your smog check is actually due

Your smog check due date is tied to your vehicle's registration expiration date, not to a calendar year. If your registration expires on March 15, your smog check must be completed before that date. You can take the test up to 90 days before your registration expires, so you have a window to schedule it without rushing.

The Department of Motor Vehicles sends a renewal notice about 60 days before your registration expires. That notice will tell you whether a smog check is required. If you miss the important date and try to renew without a passing test, the DMV will reject your renewal process and you'll have to complete the test before resubmitting. Driving with an expired registration is a violation, so it's worth marking your calendar when you get that notice.

Vehicles that don't need smog checks

Several categories of vehicles are exempt from California smog checks. All battery electric vehicles are permanently exempt. Plug-in hybrid electric vehicles (PHEVs) are also exempt. Motorcycles, motorized bicycles, and trailers don't require smog checks. Vehicles that are 40 years old or older are exempt, as are vehicles registered as classic cars or street rods under California's special registration programs.

Vehicles with fewer than 6,000 miles on the odometer are exempt from their first smog check only — they still need checks every two years after that. If you own a vehicle you believe is exempt, confirm the exemption with the DMV or a smog technician before you skip a test. Attempting to register a vehicle that requires a smog check without one will delay your renewal and may result in late fees.

What happens if you fail a smog check

If your vehicle fails a smog check, you have 30 days to repair it and retest at no additional charge from the same testing station. The technician will give you a detailed report showing which emissions standards your vehicle didn't meet. You can take that report to a repair shop to help them diagnose the problem. Common failures involve the oxygen sensor, catalytic converter, or fuel system issues.

After repairs, you return to the same smog station for a retest. If it passes, you get a certificate of compliance. If it fails again, you have another 30 days and another free retest. If your vehicle fails twice, you may be able to use the Smog Check Referee Program, which allows you to have a state referee test your vehicle under different conditions. The referee can issue a certificate even if the vehicle doesn't fully meet standards, depending on the repairs you've made and the cost of further fixes.

Smog checks when you buy or sell a vehicle

If you buy a used vehicle in California, the seller must provide a smog certificate dated within 90 days of the sale. The seller is responsible for getting the test done before you take ownership. If the vehicle fails, the seller must repair it or you can back out of the deal. You cannot register a used vehicle without a passing smog certificate, so this is a non-negotiable part of the purchase process.

If you're selling a vehicle, you must provide the buyer with a smog certificate or a written notice that the vehicle failed its smog check. If the vehicle failed, you must disclose that in writing. The buyer then decides whether to proceed with the purchase, ask you to repair it, or walk away. Some dealers will handle smog checks as part of the sale, but private sellers are responsible for arranging and paying for the test.

How to find a smog check station

California has two types of smog check stations: regular stations and referee stations. Regular stations are run by repair shops, tire shops, and independent testing facilities. You can find one through the California Department of Consumer Affairs' online station locator, which shows stations near your address and their hours. You can also search "smog check near me" and call ahead to confirm they're open and can fit you in.

The cost of a smog check varies by station but typically ranges from $30 to $70 for a basic test. Some stations charge more if your vehicle requires additional testing. You'll need your vehicle registration and proof of ownership. Bring your keys so the technician can start the engine and run the test. The whole process usually takes 15 to 30 minutes. If you pass, you'll get a certificate of compliance that you can use to renew your registration online or at the DMV.

Renewing your registration after a passing smog check

Once you have a passing smog certificate, you can renew your vehicle registration through the DMV website, by mail, or in person at a DMV office. Online renewal is the fastest option if you have a valid smog certificate. The DMV will ask for your vehicle identification number (VIN), current registration number, and the smog certificate number. You can usually complete the renewal in a few minutes.

If you renew by mail, include a copy of your smog certificate with your renewal form. If you renew in person, bring the original certificate or a copy. Registration renewal fees vary by vehicle weight and type but typically range from $200 to $400 per year. Once your renewal is processed, you'll receive new registration tags or a renewal notice to display on your vehicle. Keep your smog certificate for your records in case the DMV needs to verify it later.

Frequently Asked Questions

Can I get a smog check before my registration expires?

Yes. You can take a smog check up to 90 days before your registration expires. This gives you time to schedule the test and handle any repairs if needed without rushing to meet your registration important date.

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

You must continue to pass California smog checks and renew your registration as long as your vehicle is registered in California. If you move permanently, you should transfer your registration to your new state to avoid ongoing California requirements.

Do I need a smog check if I'm only renewing my registration online?

Yes, if your vehicle is due for a smog check, you must have a passing certificate before the DMV will process your online renewal. The system will reject the renewal if a smog check is required and you haven't provided one.

What if my vehicle is in the shop and I can't get it tested before my registration expires?

Contact the DMV before your registration expires and ask about a temporary extension. Some DMV offices will grant a brief extension if your vehicle is in the shop for repairs. You'll need to provide documentation from the repair facility showing the vehicle is being serviced.

Are there any vehicles that passed smog checks in other states that don't need California tests?

No. If your vehicle is registered in California, it must pass a California smog check regardless of where it was previously registered or what tests it passed elsewhere. California has its own emissions standards that are stricter than federal standards.