When California requires you to get a smog test

California requires a smog test every two years for most vehicles, with the test due on your vehicle's registration anniversary. If you drive a vehicle registered in California, you cannot renew your registration without a passing smog test result — the Department of Motor Vehicles will not issue new registration tags until the test is complete and submitted.

The two-year cycle applies to most passenger vehicles and light trucks. However, some vehicles are exempt: those nine model years old or newer (as of the current year) do not need a smog test, and vehicles registered as classic cars, motorcycles, or diesel-powered vehicles registered before 1998 have different rules. Vehicles that are brand new to California registration may have a grace period on their first test.

If you move to California from another state, you must get a smog test before you can register your vehicle in the state, regardless of when your previous registration expired. This is a one-time requirement for out-of-state vehicles entering California registration for the first time.

Key Takeaways

  • California requires a smog test every two years on your vehicle's registration anniversary, and you cannot renew registration without a passing result.
  • Vehicles nine model years old or newer are exempt from smog testing, and the exemption threshold changes each calendar year.
  • You must use a Bureau of Automotive Repair-certified smog station, which you can find through the official BAR database or by searching for "smog check station near me."
  • A smog test costs between $30 and $80 depending on your vehicle type and the station, and results are valid for 30 days before you must renew registration.
  • If your vehicle fails, you have 30 days to repair it and retest at no additional cost at the same station, or you can take it elsewhere for a second opinion.

How to find a certified smog test station

You must use a station certified by the Bureau of Automotive Repair (BAR), which is part of the California Department of Consumer Affairs. The official BAR station locator is available at the Bureau of Automotive Repair website — you can search by zip code or city to see all certified stations near you, along with their hours and phone numbers.

Not every repair shop or gas station that advertises smog testing is BAR-certified. Before you go, confirm the station's BAR certification number on the official database. Certified stations display their BAR certificate in the window, but the online database is the authoritative source. You can also call ahead to ask about wait times and whether you need an appointment.

The test itself takes 10 to 30 minutes depending on your vehicle's age and type. Bring your vehicle keys, proof of vehicle ownership (registration or title), and a valid ID. Some stations accept walk-ins; others require appointments, especially during peak renewal periods.

What happens during a smog test

The technician will connect your vehicle to an emissions analyzer that measures the exhaust coming from your tailpipe. For vehicles 1996 and newer, the test also reads your vehicle's onboard diagnostic system (OBD), which stores emissions-related trouble codes. The technician checks whether your vehicle's emissions fall within California's limits for nitrogen oxides, carbon monoxide, and particulate matter.

You do not need to do anything to prepare your vehicle beyond keeping it in normal running condition. Do not have major work done when ready before the test, and do not attempt to "clean" your emissions system with additives — these do not help and may cause problems. If your check engine light is on, the vehicle will likely fail the test, so address that first.

The test result is printed on the spot. If you pass, the station submits the result electronically to the California Department of Motor Vehicles, and you can renew your registration when ready. If you fail, you receive a written report showing which emissions standards your vehicle did not meet.

What to do if your vehicle fails the smog test

You have 30 days from the test date to repair your vehicle and retest. During this 30-day window, you can return to the same station for a free retest, or you can take your vehicle to a different certified station and pay the testing fee again. Many vehicle owners choose to get a second opinion at a different shop if the first station's diagnosis seems expensive or unclear.

The repair shop does not have to be BAR-certified — any repair facility can work on your vehicle. However, if you use a smog station's repair services, they must offer a warranty on the repairs. If you fail a second time after repairs, you may be able to enter the Smog Check information Program, which provides financial help for repairs on vehicles that fail twice.

If you cannot afford repairs and your vehicle is older, you may be able to trade it in or scrap it through California's vehicle retirement programs. These programs offer cash incentives for removing high-emission vehicles from the road. Contact your local air quality management district for details on programs available in your area.

Smog test costs and what affects the price

A standard smog test costs between $30 and $80 at a certified station. The price depends on your vehicle's age and type — older vehicles and diesel trucks may cost more because they require different testing procedures. Some stations charge a flat rate; others charge by the type of test your vehicle needs.

If you fail and need a retest at the same station within 30 days, the retest is free. If you go to a different station, you pay the full testing fee again. Repairs are separate from the test cost and vary widely depending on what your vehicle needs — anything from a new oxygen sensor ($100 to $300) to a catalytic converter ($400 to $1,200) or engine work.

Some stations offer package deals that bundle testing and basic repairs, but read the terms carefully. You are not required to use the same station for repairs, and you can shop around for repair quotes before committing to work.

Renewing your registration after a passing smog test

Once your vehicle passes the smog test, the station submits the result electronically to the California Department of Motor Vehicles. You can renew your registration online at the DMV website, by mail, or in person at a DMV office. The smog test result is valid for 30 days, so you must complete your registration renewal within that window.

If your registration expires before you renew, your vehicle is no longer legally registered and you cannot drive it on public roads. You can still renew after expiration, but you may face a late fee. If your registration has been expired for more than a year, you may need to pay a vehicle registration reinstatement fee in addition to the renewal cost.

You do not need to bring the smog test paperwork to the DMV — the result is already in their system. However, keep your receipt from the smog station for your records in case there are questions about the test date or results.

Vehicles exempt from California smog testing

Vehicles that are nine model years old or newer do not require a smog test. This threshold changes each calendar year — for example, in 2024, vehicles 2015 and newer are exempt. Check your vehicle's model year against the current year to determine if you are exempt. The California DMV website lists the current exemption year.

Motorcycles, motorized bicycles, and vehicles with a Gross Vehicle Weight Rating over 14,000 pounds have different testing rules or are exempt entirely. Vehicles registered as classic cars (usually 40 years or older) are also exempt, though they must be registered under the classic car classification. Diesel vehicles registered before 1998 are exempt, but newer diesel vehicles must be tested.

If you are unsure whether your vehicle is exempt, check your registration notice or call the California DMV at 1-800-777-0133. The DMV will tell you whether your vehicle needs a smog test before you can renew.

Frequently Asked Questions

Can I renew my registration without a smog test if my vehicle is exempt?

Yes. If your vehicle is nine model years old or newer, you can renew your registration online, by mail, or at a DMV office without submitting a smog test result. The DMV will not ask for one. However, if you are unsure whether your vehicle qualifies for the exemption, contact the DMV before renewing to confirm.

What if I move out of California before my smog test is due?

You do not need a smog test to cancel your California registration or transfer your vehicle to another state. However, if you want to renew your California registration before you move, you must have a passing smog test. Once you register your vehicle in another state, California's smog test requirement no longer applies.

Can I get a smog test before my registration anniversary?

Yes. You can get a smog test up to 90 days before your registration expires. The result will be valid when your registration renewal is due. This is useful if you want to get the test done early and avoid the rush near your renewal date.

What happens if I drive without a valid registration because I failed the smog test?

Driving without valid registration is a violation. You have 30 days from your failed test to repair your vehicle and retest. If you cannot complete repairs in time, contact the DMV about a registration extension or temporary permit options in your area.

Do I need to get a smog test if I only drive my vehicle occasionally?

Yes. The smog test requirement is based on your registration renewal date, not how often you drive. If your registration is due and you want to keep the vehicle registered in California, you must have a passing smog test, regardless of mileage or usage.