What Smog Check is and who has to get one

California's Smog Check is an emissions test that measures whether your vehicle's exhaust meets state pollution standards. You need one every two years if your car is registered in California and is at least four model years old. The test itself takes about 10 minutes and costs between $30 and $50 depending on your location and vehicle type.

Not every vehicle requires a Smog Check. Vehicles that are three model years old or newer are exempt. Diesel trucks registered after 1997 need a different test called the Diesel Smog Check. Electric vehicles and hydrogen fuel cell vehicles are also exempt. If you're buying a used car in California, the seller must provide proof of a passing Smog Check from within the last 90 days before you can register it.

Key Takeaways

  • California requires a Smog Check every two years for vehicles at least four model years old, with some exceptions for newer and alternative-fuel vehicles.
  • You can get tested at any Bureau of Automotive Repair-certified smog station, and the test costs $30 to $50 depending on your vehicle and location.
  • If your vehicle fails, you have 30 days to fix the problem and retest at no additional charge at the same station.
  • You cannot register or renew your vehicle registration without a passing Smog Check result, and the test must be completed within 90 days of your registration renewal date.
  • Gross polluters — vehicles that fail twice in a row — face stricter requirements and may be subject to additional repairs or removal from the road.

Finding a certified smog station and scheduling your test

Any station certified by California's Bureau of Automotive Repair can perform your Smog Check. You can search for stations near you on the Bureau of Automotive Repair website by entering your ZIP code. Most independent repair shops, dealerships, and dedicated smog stations offer the service, and many do not require an appointment — you can walk in during business hours.

Bring your vehicle registration and a valid ID when you go. The technician will run your vehicle through a computerized test that measures nitrogen oxides, particulate matter, and other pollutants in your exhaust. The entire process usually takes 10 to 15 minutes. Your test results are reported electronically to the California Department of Motor Vehicles, so you do not need to print or carry a paper certificate.

What happens if your vehicle fails the test

If your vehicle fails, the smog station will give you a detailed report showing which emissions standards you did not meet. You then have 30 days to have the problem repaired and return to the same station for a free retest. 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 that performed your initial test — you can take your vehicle to any mechanic you trust. However, you must return to the original smog station for your retest within 30 days. If you pass the retest, your registration can proceed. If you fail again, your vehicle is flagged as a gross polluter, and you will face additional requirements before you can register it.

Gross polluter status and what it means

A vehicle becomes a gross polluter if it fails the Smog Check twice in a row within a 12-month period. Once flagged, your vehicle cannot be registered until you complete a Gross Polluter Repair Program. This program requires you to spend a minimum amount on repairs — typically $500 to $1,000 depending on your vehicle's age and value — and then pass a retest.

If your vehicle is a gross polluter, you must obtain a Gross Polluter Repair Program certificate from a participating repair shop before you can renew your registration. Some repair shops specialize in this program and can guide you through the process. If repairs are not economically feasible, you may be required to remove the vehicle from the road or scrap it, though California offers some information programs for low-income vehicle owners facing this situation.

Timing your test with vehicle registration renewal

Your Smog Check must be completed within 90 days before your registration renewal date. You can find your renewal date on your vehicle registration card. If you renew your registration online or by mail, you must have a passing Smog Check result on file with the Department of Motor Vehicles before you submit your renewal.

Plan to get your test done in the month before your renewal is due. This gives you time to address any failures and retest if needed. If you wait until the last week, a failure leaves you scrambling to find a repair shop and get a retest done before your registration expires. Driving with an expired registration is illegal and can result in fines.

Smog Check for different vehicle types

Most gasoline-powered passenger cars, SUVs, and light trucks follow the standard Smog Check process described above. Diesel vehicles registered after 1997 take a different test that measures particulate matter and opacity rather than the same emissions standards as gasoline vehicles. Motorcycles registered after 1975 also require a Smog Check, though the test is simpler and often costs less.

Hybrid vehicles take the same test as gasoline vehicles. Electric vehicles and hydrogen fuel cell vehicles are permanently exempt from Smog Check requirements. If you own a vehicle that runs on alternative fuels like compressed natural gas, check with the Bureau of Automotive Repair website to confirm your vehicle's specific requirements, as rules vary by fuel type and model year.

What to do if you cannot pass the test

If your vehicle repeatedly fails despite repairs, or if the cost of repairs exceeds the vehicle's value, you have limited options. You cannot legally register the vehicle in California without a passing test. Some owners choose to sell the vehicle to a salvage yard or scrap dealer. California's Consumer information Program offers rebates and loans to low-income vehicle owners who need to replace a vehicle that cannot pass emissions standards, though funding and may be able to access vary by year.

Before giving up on a vehicle, get a second opinion from a different repair shop. Some shops specialize in emissions repairs and may identify a less expensive fix than the first shop suggested. You can also contact your local air quality management district for resources or referrals to repair information programs in your area.

Frequently Asked Questions

Can I get a Smog Check before my registration renewal date?

Yes, but it must be within 90 days of your renewal date to count. If you test more than 90 days early, you will need to retest closer to your actual renewal date. Testing too early wastes money and time.

What if I move out of California after getting a Smog Check?

Your Smog Check is only valid for California registration. If you move to another state, you will need to follow that state's emissions requirements instead. You cannot transfer a California Smog Check to another state's registration system.

Do I need a Smog Check if I only drive my vehicle occasionally?

Yes, if your vehicle is registered in California and meets the age requirement, you need a Smog Check every two years regardless of how often you drive it. Registration renewal triggers the requirement, not mileage or usage.

What if the smog station says my vehicle cannot be tested?

Some vehicles cannot be tested if they are too damaged, have missing parts, or have safety issues that prevent safe operation. The station will explain why and may refer you to a repair shop. You must address the safety issue before testing can occur.

How long does it take to get my test results?

Results are reported electronically to the Department of Motor Vehicles when ready after testing. You can see your results online through the DMV website or by calling the smog station. You do not need to wait for a paper certificate.