What California's Smog Check Requires

California requires a smog check — an emissions test that measures whether your vehicle's exhaust meets state pollution standards — before you can register or renew registration for most vehicles. The requirement applies to cars, trucks, and motorcycles model year 1976 and newer. You must pass the test and provide proof to the Department of Motor Vehicles (DMV) before your registration becomes valid.

The test itself takes about 10 to 30 minutes at a licensed smog check station. A technician connects your vehicle to a machine that reads emissions data from your engine's computer and, on older vehicles, may perform a tailpipe test. You either pass, fail, or receive a conditional pass (which means you passed but your vehicle is borderline and will need retesting in a year).

Smog checks are required every two years for most vehicles, though some newer cars and certain low-emission vehicles may may have access to for longer intervals or exemptions. The timing depends on when you first registered the vehicle and your vehicle's model year and type.

Key Takeaways

  • California requires a smog check every two years for most vehicles model year 1976 and newer before you can register or renew.
  • The test costs between $30 and $70 at a licensed smog check station and takes 10 to 30 minutes.
  • You must pass the test and bring proof of passing to the DMV; a failing vehicle cannot be registered until repairs are made and it passes a retest.
  • Some newer vehicles, electric vehicles, and vehicles under 6,000 pounds registered for the first time may be exempt or have different testing schedules.
  • If you fail, you have 30 days to repair and retest at no additional cost at the same station.

When Your Vehicle Needs a Smog Check

The requirement depends on your vehicle's age and registration history. If you are registering a vehicle for the first time in California, you do not need a smog check. However, when you renew that registration, the timing of your first smog check depends on your vehicle's model year: vehicles model year 2000 and newer do not need a smog check until their fourth registration renewal, while vehicles model year 1999 and older need one at the second renewal.

After that first test, most vehicles need a smog check every two years at renewal time. Some vehicles may have access to for a four-year interval: this applies to vehicles model year 2008 and newer that are registered in their first four years of life. Vehicles model year 2010 and newer that are registered in their first six years may also may have access to for extended intervals.

Certain vehicles are exempt entirely. These include electric vehicles, vehicles over 10,000 pounds, vehicles registered as off-highway only, and some vehicles registered as classic cars or for off-road use. Check your vehicle's registration documents or call your local DMV office to confirm your vehicle's testing schedule.

Where to Get Your Smog Check and What It Costs

You must use a licensed smog check station — not all repair shops are licensed to perform the test. The DMV maintains a searchable list of licensed stations on its website. You can search by zip code or station name. The test costs between $30 and $70 depending on the station and your vehicle type; the state does not set a fixed price, so costs vary.

Bring your vehicle's registration documents and proof of insurance. The technician will connect your vehicle to the emissions testing equipment and run the test. If your vehicle passes, you receive a certificate of compliance that is valid for 30 days. You must bring this certificate to the DMV or submit it online when you renew your registration.

Some stations offer additional services like pre-inspection consultations or repairs if your vehicle fails. However, you are not required to use the same station for repairs — you can take your vehicle to any repair shop, then return to any licensed station for a retest. If you fail, you have 30 days from the test date to repair and retest at no additional charge at the same station.

What Happens If Your Vehicle Fails the Smog Check

A failing vehicle cannot be registered until it passes a retest. You have 30 days from the test date to make repairs and return to the same station for a free retest. The station must allow you to retest at no cost within that 30-day window, even if you take your vehicle elsewhere for repairs.

Common reasons for failure include a faulty oxygen sensor, a malfunctioning catalytic converter, a check engine light that is on, or a fuel cap that is not sealing properly. Many of these repairs cost between $100 and $500, though some can be more expensive. If you are unsure what needs repair, ask the smog check technician for a detailed report — they must provide one if you ask.

If your vehicle fails a second time, you may be may be able to access for the California Consumer information Program (CCAP), which provides repair cost information or vehicle replacement for low-income owners of vehicles that repeatedly fail emissions tests. You must meet income requirements and your vehicle must have failed at least twice. Contact your local air quality management district to learn whether you may have access to.

Exemptions and Special Cases

Electric vehicles (EVs) and plug-in hybrid electric vehicles (PHEVs) are exempt from smog checks. Vehicles registered as classic cars or street rods may have different requirements — check with your local DMV. Vehicles over 10,000 pounds registered as commercial vehicles are also exempt, as are vehicles registered for off-highway use only.

If your vehicle is in the shop for repairs and your registration is about to expire, you can request a temporary registration extension from the DMV. This does not exempt you from the smog check requirement, but it gives you time to complete the test and repairs before your registration lapses.

If you are moving out of California, you do not need a smog check to cancel your registration. If you are moving into California from another state, your out-of-state registration is valid for 20 days; after that, you must register with California and obtain a smog check according to the schedule for your vehicle's model year.

How to Submit Your Smog Check Certificate to the DMV

Once you pass the smog check, you receive a certificate of compliance valid for 30 days. You can submit it to the DMV in three ways: online through the DMV website, by mail, or in person at a DMV office. Online submission is the fastest — you can renew your registration and submit your certificate on the same day.

To submit online, visit the DMV website, select vehicle registration renewal, and enter your certificate number and vehicle information. You will need your vehicle's license plate number, VIN, and the smog check certificate number. Payment for registration renewal is separate from the smog check cost.

If you submit by mail, include your certificate, your renewal notice, and payment. Mail to the address listed on your renewal notice. If you submit in person, bring your certificate and renewal notice to any DMV office. Processing times vary: online submissions are typically processed within a few days, while mail submissions may take two to three weeks.

Frequently Asked Questions

Can I get a smog check before my registration renewal is due?

Yes. You can take your vehicle for a smog check up to 90 days before your registration expires. The certificate is valid for 30 days, so timing matters — if you test too early, your certificate will expire before you can submit it to the DMV. Most people test within 30 days of their renewal date.

What if I buy a used car from a private seller in California?

If the vehicle is already registered in California, the seller's registration must be current and the vehicle must have passed its most recent smog check. When you transfer the title to yourself, you must renew the registration, which will require a smog check if one is due according to the vehicle's schedule. The DMV will tell you whether a test is required when you explore for transfer.

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

Yes. The requirement is based on your registration renewal date, not how often you drive. If your registration is due for renewal and a smog check is required for your vehicle's model year, you must pass one before the DMV will renew your registration — even if the vehicle sits unused most of the time.

What if the smog check station gives me a conditional pass?

A conditional pass means your vehicle passed but is borderline on emissions standards. You can register your vehicle with a conditional pass, but you must return for a retest in one year. If you fail that retest, you then have 30 days to repair and retest.

Can I dispute a smog check failure?

You can request a second opinion by taking your vehicle to a different licensed smog check station for another test. If the second station also finds a failure, you will need repairs. If the second station passes your vehicle, contact your local air quality management district — they can investigate the first station's testing procedures.