How often you need a smog check in California depends on your vehicle's age and type

Most vehicles registered in California need a smog check every two years. The exact timing depends on when your vehicle was first registered in the state and whether it's a passenger car, truck, or motorcycle. Vehicles registered before 1975 are exempt. Diesel vehicles have different rules than gasoline vehicles. The California Department of Consumer Affairs oversees the smog check program, and your local Bureau of Automotive Repair can tell you whether your specific vehicle is due.

Your registration renewal notice will tell you if a smog check is required before you can renew. If the notice says "smog check required," you must get one within 90 days before your registration expires. You cannot renew your registration without proof of a passing smog check.

Key Takeaways

  • Most California vehicles need a smog check every two years, timed to your registration renewal date.
  • Vehicles from 1975 and earlier, electric vehicles, and some newer low-emission vehicles are fully exempt.
  • Your registration renewal notice tells you whether a smog check is required and when it must be completed.
  • You have 90 days before your registration expires to get a smog check, but waiting until the last month creates scheduling pressure.
  • Diesel vehicles and vehicles over 14,000 pounds have separate smog check rules and may test less frequently.

Two-year cycle for most passenger vehicles

If you own a gasoline-powered passenger car, truck, or SUV registered in California after 1975, you will need a smog check every two years. The check is due in the same month your vehicle registration renews. If your registration renews in March, your smog check must be completed by March of that year.

The California Bureau of Automotive Repair maintains a list of certified smog check stations. You can find one near you by searching the Bureau's website or asking your mechanic. The test typically costs between $30 and $80, depending on the station and your vehicle type. A passing smog check is valid for 30 days, so you can get tested up to 90 days before your registration expires and still have time to renew.

Vehicles exempt from smog checks

Several categories of vehicles do not need smog checks at all. Vehicles manufactured before 1975 are permanently exempt. All battery electric vehicles and hydrogen fuel cell vehicles are exempt. Motorcycles registered in California do not require smog checks.

Some newer vehicles may also be exempt based on their emissions rating. Vehicles that meet California's Super Ultra Low Emission Vehicle (SULEV) standard or Zero Emission Vehicle (ZEV) standard may not need a smog check, depending on the model year. Your registration renewal notice will clearly state whether your vehicle is exempt. If you are unsure, contact the Bureau of Automotive Repair or check your renewal notice before paying for a test you may not need.

Diesel vehicles and heavy trucks

Diesel vehicles follow different smog check rules than gasoline vehicles. Diesel passenger cars and light trucks registered after 1997 need a smog check every two years, the same as gasoline vehicles. However, diesel vehicles registered before 1998 are exempt from smog checks.

Vehicles over 14,000 pounds gross vehicle weight rating (GVWR) are subject to the Heavy-Duty Vehicle Inspection Program instead of the standard smog check. These vehicles may test less frequently or follow a different schedule. If you own a commercial truck or heavy vehicle, your registration notice will specify which program applies to you.

What happens if you miss your smog check important date

If your registration renewal notice requires a smog check and you do not complete one before your registration expires, you cannot legally renew your registration. The California Department of Motor Vehicles will not process your renewal without proof of a passing smog check.

If you are driving with an expired registration, you can be cited by law enforcement. The fine for driving with an expired registration starts at $100 and increases if you do not correct it. If your vehicle fails the smog check, you have 30 days to repair it and retest. Some repair shops offer free or discounted retests if your vehicle fails the first time.

How to learn about your vehicle needs a smog check

The simplest way to know whether your vehicle needs a smog check is to look at your registration renewal notice. The notice will clearly state "smog check required" or "smog check not required." If you have lost your renewal notice, you can check the California Department of Motor Vehicles website or call your local DMV office with your vehicle's license plate number.

You can also contact the Bureau of Automotive Repair directly. They maintain records of which vehicles are subject to smog checks based on model year, fuel type, and registration history. If you recently moved to California or are registering a vehicle for the first time, the DMV will tell you at registration whether smog checks are required going forward.

Planning ahead to avoid last-minute stress

Many people wait until the last week before their registration expires to schedule a smog check. This creates long wait times at testing stations and leaves no time to repair a vehicle that fails. A better approach is to schedule your smog check two to three months before your registration expires.

If your vehicle fails, you will have time to take it to a mechanic, identify the problem, and retest before your registration important date. If you know your vehicle has been running poorly or has a check engine light, get it inspected by a mechanic before scheduling the smog check. Fixing the underlying problem first increases the chance of passing on the first attempt.

Frequently Asked Questions

Can I get a smog check more than 90 days before my registration expires?

Yes, you can get a smog check at any time. However, the results are only valid for 30 days. If you test more than 90 days before your registration expires, your results will expire before you can renew. Schedule your test within 90 days of your registration renewal date to may support the results are still valid when you renew.

What if my vehicle fails the smog check?

You have 30 days from the test date to repair your vehicle and retest. The repair shop does not have to be the same place where you tested. Many certified smog check stations also perform repairs, and some offer free retests if you repair the vehicle with them. Keep your failing test report — you will need it to show the retest station.

Do I need a smog check if I just bought a used car in California?

If the vehicle's registration is current and valid, you do not need a smog check until the next renewal date shown on the registration. However, if the registration has expired or you are registering an out-of-state vehicle in California for the first time, you will need a smog check as part of the registration process.

Can I renew my registration online without a smog check?

No. If your renewal notice requires a smog check, you cannot complete the renewal online or by mail without submitting proof of a passing smog check first. You must provide the smog check certificate number or upload the passing test report through the DMV website or in person at a DMV office.

Are there any vehicles that need smog checks more than every two years?

No. The standard cycle for all vehicles that require smog checks is every two years. Some vehicles are exempt entirely, but no vehicle registered in California is required to test more frequently than every two years.