California requires a smog check every two years for most vehicles, and every year for vehicles over 8 model years old
A smog check is an emissions test that measures whether your vehicle's exhaust meets California air quality standards. The state runs this program through licensed smog check stations — not the DMV, not a state office, but independent repair shops and testing facilities you find in your neighborhood.
You need a smog check before you can renew your vehicle registration with the DMV. If you skip it, your registration renewal will be rejected. The test itself costs between $30 and $80 depending on your vehicle type and the station you choose.
The frequency depends on your vehicle's age and type. Most passenger vehicles need a test every two years. Vehicles manufactured more than 8 model years before the current year need one every year. Diesel vehicles, motorcycles, and vehicles registered in their first four years of ownership have different rules.
Key Takeaways
- You need a smog check before renewing your vehicle registration, and the DMV will reject your renewal if you do not have a passing test result.
- Most vehicles need a smog check every two years; vehicles over 8 model years old need one every year.
- You must go to a licensed smog check station, not the DMV or a state office — find one through the Bureau of Automotive Repair website or by searching your area.
- A passing test result is valid for 30 days, so schedule your smog check close to when you plan to renew your registration.
- If your vehicle fails, you have 30 days to fix the problem and retest at no additional charge at the same station.
When your vehicle needs a smog check
The year your vehicle was manufactured determines the testing schedule. Count back from the current year: if your vehicle is 8 or more model years old, you need a smog check every year. If it is newer than that, you need one every two years.
Some vehicles are exempt entirely. These include vehicles registered for the first time in California (they get a four-year grace period), electric vehicles, motorcycles, vehicles over 55,000 pounds, and vehicles registered as non-operational. If you are unsure whether your vehicle is exempt, the Bureau of Automotive Repair website has a full list organized by vehicle type.
Your smog check is due before your registration expires. The DMV will not renew your registration without proof of a passing test, so plan to get tested in the month before your registration renewal date.
How to find a licensed smog check station
You cannot get a smog check at a random repair shop. The station must be licensed by the Bureau of Automotive Repair, which is part of the California Department of Consumer Affairs. The Bureau maintains a searchable database on its website where you can enter your zip code and see all licensed stations near you.
When you call or visit a station, confirm three things: that they are licensed, that they test your vehicle type (some stations test only gasoline vehicles, for example), and their current wait time. Many stations can test you the same day, but during peak renewal periods in your area, you may need to schedule ahead.
Bring your vehicle registration and a valid ID. The test takes 10 to 30 minutes depending on whether your vehicle passes on the first try. You will receive a printed test result on the spot.
What happens if your vehicle fails the smog check
If your vehicle fails, you have 30 days to repair the problem and return to the same station for a retest at no additional charge. The station will give you a written report explaining which emissions standards your vehicle did not meet.
Common failure reasons include a faulty oxygen sensor, a loose gas cap, a malfunctioning catalytic converter, or an engine light that is on. A repair shop can diagnose the specific problem, though you are not required to use the same station for repairs — you can take your vehicle anywhere.
If you repair the vehicle and retest within 30 days at the original station, the retest is free. After 30 days, you must pay the full test fee again. Keep your test result paperwork until your registration is renewed, in case the DMV asks for proof.
How to submit your smog check result to the DMV
The smog check station submits your test result electronically to the DMV on your behalf — you do not need to mail anything or upload anything yourself. The result appears in the DMV's system within one business day.
When you renew your registration online, by mail, or in person at a DMV office, the system automatically checks for your smog check result. If it is there and you passed, your renewal will process. If the result is not showing up after a few days, contact the smog check station to confirm they submitted it correctly.
Your smog check result is valid for 30 days from the test date. If your registration renewal is more than 30 days away, you can wait to get tested closer to your renewal date — there is no advantage to testing early.
Smog check requirements for different vehicle types
Passenger cars and light trucks follow the standard two-year or one-year schedule described above. Diesel vehicles have a separate program with different emissions standards and are tested at stations specifically licensed for diesel testing.
Motorcycles are exempt from smog checks in California. Vehicles registered as non-operational do not need a smog check. Vehicles over 55,000 pounds are exempt. Hybrid and electric vehicles have different rules — some hybrids still need a smog check, while all-electric vehicles are exempt.
If you own a vehicle that does not fit the standard categories, the Bureau of Automotive Repair website lists the specific rules for your vehicle type. You can also call a licensed smog check station in your area and describe your vehicle; they can tell you whether a test is required.
What to do if you cannot get a smog check before your registration expires
If your registration expires before you can get a smog check, you cannot legally drive the vehicle. The DMV will not renew your registration without a passing test result.
If you are having trouble finding an available appointment, try stations in neighboring zip codes or cities — you do not have to use a station in your own area. You can also call the Bureau of Automotive Repair at 1-800-952-5210 to ask for help locating a station with availability.
If your vehicle fails and you cannot afford repairs when ready, you have 30 days to fix it and retest. During that time, you can still renew your registration once you pass the retest. If you need more than 30 days, you will need to register the vehicle as non-operational or out-of-state until repairs are complete.
Frequently Asked Questions
Can I get a smog check before my registration renewal is due?
Yes, but the result is only valid for 30 days. If you test more than 30 days before your registration expires, you will need to test again before renewing. Most people test in the month before their registration renewal date to keep the result valid.
What if I just bought a used car and do not know when the last smog check was?
The seller should have provided a smog check result as part of the sale. If they did not, you will need a new smog check before you can register the vehicle in California. The test is required before registration, not after, so you cannot legally drive it until you pass.
Do I need a smog check if I am renewing my registration by mail?
Yes. The DMV checks for a passing smog check result whether you renew online, by mail, or in person. The smog check station submits your result electronically, so the DMV will see it regardless of how you choose to renew.
What if the smog check station says my vehicle cannot be tested?
Some stations do not have equipment for certain vehicle types, such as diesel vehicles or vehicles with unusual engine configurations. Call another licensed station in your area — they may be able to test your vehicle. If no station in your area can test it, contact the Bureau of Automotive Repair for guidance.
Can I drive my vehicle if it fails the smog check?
Yes, you can drive it during the 30-day retest period while you arrange repairs. However, you cannot renew your registration until you pass. If your registration expires during the 30 days, you cannot legally drive the vehicle until you pass the retest and renew.