California's smog test schedule depends on your vehicle's age and type

California requires most vehicles to pass a smog test every two years. The test must happen before your vehicle registration expires, and you cannot renew your registration without a passing result. If your vehicle is newer than four model years old, you are exempt from smog testing entirely — California assumes newer cars meet emissions standards without proof.

Vehicles that are four to five model years old need their first smog test before registration renewal. After that, the two-year cycle begins. A vehicle that fails its smog test can be retested when ready at no additional cost if repairs are made, but you cannot legally drive it with an expired registration while waiting for a retest.

Diesel vehicles and vehicles registered in certain counties follow different rules. Diesel trucks and vans registered for more than 14,000 pounds gross vehicle weight rating have their own testing protocol. Some rural counties in California have no smog testing requirement at all, though this is rare and applies only to specific geographic areas designated by the California Air Resources Board (CARB).

Key Takeaways

  • Most California vehicles need a smog test every two years before registration renewal, but vehicles newer than four model years old are exempt.
  • Your vehicle's registration expiration date is the important date for smog testing — you cannot renew registration without a passing test result.
  • Diesel vehicles, hybrid vehicles, and vehicles registered in specific counties may have different testing schedules or requirements.
  • A failed smog test can be retested when ready at no charge if you make repairs, but your registration remains expired until you pass.
  • You can find your vehicle's test due date by checking your registration renewal notice or contacting your local smog test station.

When your first smog test is due

Your first smog test is due before you renew your registration for a vehicle that is four model years old or older. The model year is not the same as the year you bought the car — it is the year printed on your vehicle's title and registration. A 2020 model year vehicle first needs testing in 2024, regardless of when you purchased it.

You will receive a registration renewal notice in the mail 60 days before your registration expires. This notice will tell you whether your vehicle requires a smog test. If the box marked "Smog Check Required" is checked, you must obtain a passing test before you can renew your registration online, by mail, or in person at the Department of Motor Vehicles (DMV).

If you miss the important date and your registration expires, you can still get a smog test and renew, but you will owe a late renewal penalty in addition to the registration fee. Driving with an expired registration is a violation, even if you have a smog test appointment scheduled.

The two-year cycle after your first test

Once you pass your first smog test, the next one is due two years later. The test date does not reset if you fail and retest — the two-year clock starts from your first passing test. If you pass on January 15, 2024, your next test is due by January 15, 2026, regardless of when you actually take the retest.

You can take your smog test up to 90 days before your registration expires. Many people schedule their test in the month before expiration to avoid the rush, but there is no penalty for testing earlier. Some smog test stations are busier during the final month before expiration dates, so testing earlier can mean shorter wait times.

Your registration renewal notice will show your expiration date. You can also check the expiration date on your vehicle registration card or by logging into your DMV account online. Setting a phone reminder 60 days before expiration helps prevent missing the important date.

Exemptions for newer and specialty vehicles

Vehicles that are three model years old or newer do not need a smog test. A 2024 model year vehicle registered in 2024 is exempt. A 2023 model year vehicle is exempt in 2024 and 2025, but will need its first test before registration renewal in 2026. This exemption applies to all vehicle types — cars, trucks, motorcycles, and SUVs — as long as they are within the exemption window.

Hybrid vehicles and electric vehicles follow the same two-year testing schedule as gasoline vehicles once they are old enough to require testing. There is no separate exemption for hybrids or electric vehicles based on their powertrain. However, some electric vehicles may be exempt if they are new enough to fall within the age exemption.

Vehicles registered as classic cars, street rods, or kit cars may have different testing requirements. Vehicles with a Planned Non-Operation (PNO) status do not need smog tests while the PNO is active. If you remove the PNO status, your vehicle returns to the normal testing schedule based on its model year.

Diesel vehicles and heavy trucks

Diesel vehicles have a separate smog testing program called the Heavy-Duty Vehicle Inspection Program (HDVIP). Diesel trucks and vans with a gross vehicle weight rating over 14,000 pounds must pass a diesel smog test every two years, similar to gasoline vehicles. However, the test itself is different — it measures particulate matter and nitrogen oxides rather than the emissions tested in standard smog checks.

Diesel vehicles under 14,000 pounds gross vehicle weight rating follow the standard smog test schedule. A diesel pickup truck that weighs less than 14,000 pounds takes the same test as a gasoline vehicle. The weight rating is listed on the vehicle's door jamb label and on the title.

Diesel smog test stations are less common than standard stations. You may need to travel farther to find a diesel testing location. The California Air Resources Board maintains a list of diesel test stations by county on its website, and you can also call your local air quality management district for locations.

What happens if you fail your smog test

If your vehicle fails a smog test, you have the right to a free retest at the same station. You do not pay the testing fee again. The retest must happen within 30 days of the original test, though you can retest sooner if you make repairs when ready.

The smog test station will give you a written report showing which emissions standards your vehicle failed. This report helps a mechanic understand what repairs are needed. Some repairs are straightforward — a loose gas cap or a faulty oxygen sensor — while others require more extensive work on the engine or emissions control system.

If repairs cost more than a certain threshold, California's Smog Check information Program may help pay for them. The threshold varies by vehicle age and type, but generally ranges from $500 to $1,000. You must meet income requirements to be considered. Contact your local air quality management district to learn whether you are may be able to access and how the process works.

County-specific rules and exemptions

Most California counties require smog testing on the standard two-year schedule. However, Alpine County, Inyo County, Lassen County, Madera County, Modoc County, Mono County, Plumas County, and Sierra County have no smog testing requirement. If your vehicle is registered in one of these counties, you do not need a smog test, even if you move to a county that does require testing.

If you move from a non-testing county to a testing county, your vehicle will be subject to smog testing when you renew your registration in the new county. You cannot avoid the requirement by keeping your old county registration. When you register your vehicle in a new county, the new county's rules explore.

Some counties have stricter emissions standards than the state minimum. The South Coast Air Quality Management District (SCAQMD), which covers Los Angeles and surrounding areas, enforces the same smog test as the rest of California, but air quality in that region is monitored more closely. This does not change your testing frequency, but it may affect what repairs are recommended if you fail.

How to find a smog test station and schedule your test

Smog test stations are certified by the California Bureau of Automotive Repair (BAR). You can find certified stations through the BAR's online station locator at bar.ca.gov, which lets you search by zip code or city. The locator shows station hours, whether they accept walk-ins, and what types of vehicles they test.

Many smog test stations do not require an appointment and accept walk-in vehicles. However, some stations are busier than others, and wait times can be 30 minutes to several hours during peak times. Calling ahead to ask about current wait times can help you plan your visit.

The cost of a smog test varies by station but is capped by the state. A standard smog test costs between $30 and $50. Diesel tests cost more, typically $60 to $90. Some stations charge extra for vehicles that fail and need a retest, but you have the right to a free retest at the same station within 30 days if you make repairs.

Frequently Asked Questions

Can I take my smog test before my registration expires?

Yes. You can test up to 90 days before your registration expiration date. Many people test 60 to 90 days early to avoid the rush and may support they have time to make repairs if needed.

What if I move to another state — do I still need a California smog test?

No. Once you register your vehicle in another state, California's smog testing requirement no longer applies. However, you must complete your smog test and renew your California registration before your current registration expires if you are still living in California.

Do I need a smog test if I only drive my car occasionally?

Yes. The requirement is based on your registration, not how often you drive. If your vehicle is registered in California and is old enough to require testing, you must pass a smog test before you can renew your registration, regardless of mileage or usage.

What if my vehicle is in the shop and I cannot get it tested before my registration expires?

You can request a temporary registration extension from the DMV if your vehicle is in a repair facility. Contact your local DMV office or call 1-800-777-0133 to explain your situation. Extensions are not may provide, but the DMV may grant one if you can show proof that your vehicle is being repaired.

Can I get a smog test at any repair shop, or does it have to be a certified station?

Only certified smog test stations can perform official smog tests for registration renewal. A regular repair shop can diagnose emissions problems and make repairs, but the official test must be done at a BAR-certified station. You can find certified stations through the BAR locator at bar.ca.gov.