California requires most vehicles to pass a smog check every two years, or annually if your car is older or has failed before

A smog check is an emissions test that measures whether your vehicle's exhaust meets California's air quality standards. The state runs this program through licensed smog check stations — not through the DMV or a single state office. When you renew your vehicle registration, the DMV will not issue new tags until you show proof of a passing smog check, unless your vehicle is exempt.

The frequency depends on your vehicle's age and history. Most cars built after 1975 need a smog check every two years when you renew registration. Vehicles that fail the test must be retested annually until they pass. Diesel vehicles, motorcycles, and vehicles registered in certain counties have different rules. Vehicles older than 1975, electric vehicles, and some hybrids are exempt.

Key Takeaways

  • Most California vehicles need a smog check every two years at a licensed station, not at the DMV.
  • You must show proof of a passing test to renew your vehicle registration with the DMV.
  • Vehicles that fail must be retested annually until they pass, and you cannot legally drive with an expired smog check.
  • The test costs between $30 and $70 depending on the station and vehicle type, and results are reported electronically to the state.
  • If your vehicle fails, you have options including repairs, a second opinion from another station, or a referee inspection if you believe the test was wrong.

When your smog check is due and what happens if you miss the important date

Your smog check is due before your vehicle registration expires. The DMV will not renew your tags without proof of a passing test. You can take the test up to 60 days before your registration expires, so the results will be valid when you renew.

If your registration expires and you have not passed a smog check, you are driving with expired tags, which is illegal. The DMV will not process your renewal until you submit proof of a passing test. You cannot straightforward pay a late fee and renew — the smog check is a separate requirement. If you are pulled over with expired registration, you can face a fine.

Some counties in California have different smog check schedules. Check your registration renewal notice or the Bureau of Automotive Repair website to confirm when your test is due. The notice will tell you the exact expiration date and whether you need a smog check to renew.

Where to get a smog check and what the test costs

You must go to a licensed smog check station. These are independent repair shops, gas stations, or dedicated testing centers — not the DMV. You can search for stations near you on the Bureau of Automotive Repair website by entering your zip code. The search tool shows which stations are currently licensed and open.

The test itself costs between $30 and $70, depending on the station and your vehicle type. Diesel vehicles and trucks may cost more. This is the testing fee only — if your vehicle fails and needs repairs, that is a separate cost paid to a repair shop. Some stations offer both testing and repairs, but you can take your vehicle to any licensed station for the test and any repair shop for fixes.

The test takes about 10 to 30 minutes. The station will connect your vehicle to a machine that measures emissions from your exhaust. Results are reported electronically to the state within one business day. You will receive a receipt showing whether you passed or failed, and the state record updates automatically so the DMV can see your result when you renew registration.

What happens if your vehicle fails the smog check

If your vehicle fails, you have several options. The most common path is to have repairs made and then retest at any licensed station. You do not have to return to the same station. The repairs might be straightforward — a loose gas cap, a faulty oxygen sensor, or a spark plug issue — or they might be more involved. The station that tested your vehicle can provide a diagnostic report showing what failed, which you can take to a repair shop.

If you believe the test result was wrong, you can request a second test at a different station. This costs another testing fee, but it gives you a second opinion. If the second test also shows a failure, you know the problem is real. If the second test shows a pass, you have proof that the first result may have been an error.

If you have made repairs and still fail, or if repairs are very expensive, you can request a referee inspection through the Bureau of Automotive Repair. A referee is a state-certified inspector who can review whether the original test was conducted correctly. This costs around $70 to $100 and takes a few weeks to schedule. A referee inspection is useful if you believe the testing station made a mistake, not if your vehicle genuinely needs repairs.

Vehicles that are exempt from smog checks

Not all vehicles need a smog check. Electric vehicles are fully exempt because they produce no emissions. Plug-in hybrids and some hybrid vehicles may be exempt depending on the model year — check the Bureau of Automotive Repair website or your registration renewal notice.

Vehicles manufactured before 1975 are exempt. Motorcycles have a separate, simpler smog check process in some counties. Vehicles registered in rural counties that do not have air quality concerns may have different rules. Your registration renewal notice will tell you whether your vehicle needs a smog check.

If you believe your vehicle should be exempt but your renewal notice says you need a test, contact the DMV or the Bureau of Automotive Repair to verify. Do not skip the test without confirmation — driving with expired registration is illegal.

How smog check results are reported and what the DMV sees

When you pass a smog check, the testing station reports the result electronically to the state's Bureau of Automotive Repair within one business day. The DMV can see this record when you go to renew your registration. You do not have to print anything or mail anything — the state system connects automatically.

You will receive a paper receipt at the station showing your test result. Keep this receipt until your registration is renewed, in case there is a delay in the electronic report reaching the DMV. If you renew online or by mail, the DMV will check the state database for your smog check result. If you renew in person at a DMV office, bring your receipt as backup, though the staff can usually see the result on their computer.

If you fail a smog check, that result is also reported to the state. The DMV will not renew your registration until you show proof of a passing test. You can take the test again at any licensed station once you have made repairs.

Smog check rules for different vehicle types and counties

Most passenger cars follow the standard two-year smog check schedule. Diesel vehicles, trucks, and vehicles over a certain weight may have different testing procedures or schedules. Motorcycles in some counties can take a simpler test or may be exempt. Check your registration renewal notice or the Bureau of Automotive Repair website to confirm the rules for your specific vehicle.

Some California counties have stricter air quality standards and may require annual smog checks for all vehicles, or may test vehicles that are normally exempt. The Bay Area, South Coast, and San Joaquin Valley regions have more frequent testing in some cases. Your renewal notice will specify the schedule for your county.

If you move to a different county or register a vehicle in a new county, the smog check rules may change. When you update your registration address with the DMV, confirm whether your new county has different smog check requirements.

Frequently Asked Questions

Can I renew my registration without a smog check if I pay extra?

No. The smog check is a legal requirement, not an optional fee. The DMV will not issue new registration tags without proof of a passing test, regardless of how much you pay. If your vehicle is exempt, you do not need a test, but you cannot waive the requirement for a vehicle that is subject to it.

What if I just bought a used car and do not know when the last smog check was?

Check your registration renewal notice — it will tell you when your smog check is due. If you just bought the car, the previous owner's smog check is not your responsibility. You need to pass a test before your registration expires. If your registration is already expired, you must get a smog check before you can legally drive the vehicle.

Do I have to use the same smog check station every time?

No. You can use any licensed station. If you want a second opinion after a failure, you can go to a different station. The results are all reported to the same state database, so it does not matter which station you choose.

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

Contact the DMV before your registration expires and ask about a temporary extension or late renewal. Some situations allow a brief grace period, but you must request it before the expiration date. Do not drive with expired registration while waiting for repairs — this is illegal.

How do I know if a smog check station is actually licensed?

Use the Bureau of Automotive Repair's station search tool on their website. Enter your zip code and it will show all currently licensed stations near you. If a station is not on this list, it is not licensed and you should not use it. Licensed stations display a certificate in their window.