What California's smog check requires
California requires most vehicles to pass a smog check every two years, though the exact timing depends on when your vehicle was registered and its model year. The test measures your vehicle's exhaust emissions to confirm it meets state air quality standards. You cannot renew your vehicle registration without a passing smog check result on file with the Department of Motor Vehicles (DMV).
The smog check is performed at a Bureau of Automotive Repair (BAR) certified station — a private repair shop or smog station that has been licensed by the state. The technician will connect your vehicle to equipment that reads your engine's emissions data and runs a tailpipe test. The whole process usually takes 30 minutes to an hour.
If your vehicle passes, the station sends the results electronically to the DMV. If it fails, you receive a written report showing which emissions standards your vehicle did not meet, and you have 30 days to repair the vehicle and retest at no additional charge.
Key Takeaways
- California requires a smog check every two years for most vehicles, and you cannot renew your registration without a passing result.
- The test is performed at a BAR-certified smog station and takes about 30 minutes to an hour.
- If your vehicle fails, you have 30 days to make repairs and retest for free at the same station.
- Newer vehicles (generally 2000 and newer) and vehicles with fewer than 6,000 miles may be exempt from the test.
- You can find a certified smog station through the BAR's online locator or by searching "smog check near me" in your area.
Which vehicles are exempt from smog testing
Not every vehicle in California needs a smog check. Vehicles that are six model years old or newer are exempt — so a 2019 vehicle would not need testing in 2024. Vehicles with fewer than 6,000 miles on the odometer are also exempt, even if they are older. Diesel vehicles registered before 1998 and gasoline vehicles registered before 1975 are permanently exempt.
Electric vehicles and hydrogen fuel cell vehicles do not require smog checks. If you own a vehicle that was previously registered outside California, you may be exempt from smog testing for the first two years after you register it in the state, though you will still need to pass it before your second registration renewal.
The best way to confirm whether your specific vehicle needs testing is to check your DMV renewal notice — it will state whether a smog check is required. You can also call your local smog station or the BAR's consumer hotline at 1-800-952-5210.
How to find a certified smog station
The Bureau of Automotive Repair maintains an online directory of all licensed smog stations at bar.ca.gov. You can search by zip code or city to find stations near you. The directory shows each station's address, phone number, and hours of operation.
Many independent repair shops and gas stations also perform smog checks — look for the BAR certification notice posted in the window or ask when you call. Prices vary by station but typically range from $30 to $80 for a standard test. Some stations charge extra for vehicles that fail and need retesting, though the retest itself should be free.
Before you go, call ahead to confirm the station is open and ask about their current wait time. Bring your vehicle registration and a valid ID. If your vehicle has a check engine light on, some stations will not test you until that light is cleared, so have that diagnosed first if needed.
What happens if your vehicle fails the smog check
A failing smog check means your vehicle's emissions are above California's limits for one or more pollutants — usually nitrogen oxides, particulate matter, or hydrocarbons. The station will give you a written report listing which emissions standards were not met and the specific readings from your vehicle.
You then have 30 days to repair your vehicle and bring it back to the same station for a retest at no charge. Common repairs include replacing a faulty oxygen sensor, fixing a vacuum leak, replacing a catalytic converter, or updating the engine computer software. If repairs cost more than $500, you may be able to request a Smog Check Abatement — a waiver that allows you to register your vehicle anyway — but you must first attempt repairs and fail a second time.
If you cannot afford repairs or your vehicle is very old, the state's Consumer information Program may help cover some repair costs. Contact your local air quality management district or call the BAR hotline for information about repair information in your area.
Smog check timing and registration renewal
Your smog check is due every two years, and the DMV will not renew your registration without a passing result. The test is valid for 30 days from the date it is performed, so you should schedule it close to your registration renewal date — not months in advance.
You can renew your registration online, by mail, or in person at a DMV office, but you must have the smog check result on file first. If your registration expires before you pass the smog check, you are driving illegally and can be cited. If you know your test is coming due, schedule the smog check at least two weeks before your registration expires to allow time for repairs if needed.
If you are buying a used vehicle in California, the seller must provide you with a smog check report dated within 30 days of the sale. This report becomes part of your vehicle's history and helps you understand any emissions issues before you buy.
Smog check costs and where to find help
A standard smog check costs between $30 and $80 depending on the station and your vehicle type. Diesel vehicles and vehicles with onboard diagnostic (OBD) systems may cost slightly more. If your vehicle fails and needs repairs, costs depend entirely on what is wrong — a sensor replacement might cost $100 to $300, while a catalytic converter can run $500 to $2,000 or more.
If repair costs exceed $500, you may be able to request a Smog Check Abatement, which allows you to register your vehicle without passing the test. To may have access to, you must have attempted repairs and failed a second test. Contact your local air quality management district to request an abatement.
Some nonprofits and local government programs offer repair information for low-income vehicle owners. The BAR's website lists repair information programs by county. You can also contact your city or county environmental health department to ask about local programs that may help cover emissions repair costs.
Frequently Asked Questions
Can I get a smog check waiver if my vehicle is too old to repair?
If your vehicle fails the smog check and repair costs exceed $500, you can request a Smog Check Abatement. You must first attempt repairs and fail a second test to may have access to. Contact your local air quality management district with your failed test reports to request the waiver.
What if I just bought a used car and it failed the smog check?
If you bought the vehicle within 30 days and it has a failed smog check report, you may have grounds to return it or negotiate repairs with the seller. California law requires the seller to provide a smog check report dated within 30 days of sale. Contact the seller or a consumer protection attorney if you believe you were sold a vehicle that does not meet emissions standards.
Do I need a smog check if I'm registering a vehicle for the first time in California?
New vehicles do not need a smog check for their first registration. Vehicles registered outside California may be exempt from testing for the first two years after you register them in California, though you will need to pass before your second renewal. Check your DMV renewal notice to confirm whether testing is required.
What should I do if the smog station says my vehicle cannot be tested?
Some stations will not test vehicles with a check engine light on, excessive exhaust smoke, or other obvious problems. Have the check engine light diagnosed and repaired first, then return to the station. If the station refuses to test for another reason, contact the BAR at 1-800-952-5210 to report the issue and find another certified station.
Can I test my vehicle early to get ahead of my registration important date?
Yes, but the smog check result is only valid for 30 days. If you test too early and then fail, you may not have time to repair and retest before your registration expires. Schedule your test within two weeks of your registration renewal date to give yourself time for repairs if needed.