What Smog Check requires in Riverside County

Riverside County requires a smog check (also called an emissions test) every two years for most vehicles, or annually for vehicles model year 1975 and older. The test measures what your vehicle's exhaust contains — primarily nitrogen oxides and particulate matter — to confirm it meets California's emissions standards.

You need a smog check before you can register or renew registration with the California Department of Motor Vehicles (DMV). If your vehicle fails, you cannot complete registration until you repair it and pass a retest. The test itself costs between $30 and $70 depending on the testing station, and a retest after repairs costs the same.

Riverside County is part of the South Coast Air Quality Management District (SCAQMD), which enforces stricter emissions rules than many other California regions because of persistent air quality challenges. This means the standards your vehicle must meet are the same statewide, but the testing frequency and vehicle age thresholds may differ slightly from other air districts.

Key Takeaways

  • Riverside County requires a smog check every two years for most vehicles, or every year for vehicles model year 1975 and older.
  • You must pass a smog check before the DMV will register or renew your vehicle registration.
  • Testing stations are certified by the state and display a "STAR" decal; you can find them through the Bureau of Automotive Repair website or by searching online.
  • If your vehicle fails, you have 30 days to repair it and return to any testing station for a retest at no additional inspection fee.
  • Vehicles with a "Check Engine" light on will automatically fail the smog check and must be repaired before testing.

When your vehicle is due for a smog check

Your smog check is due every two years from the date of your last passing test, not from your registration renewal date. The DMV will not let you renew registration without a current passing smog check on file. You can take your vehicle for testing up to 30 days before your registration expires, and the new test date becomes your new two-year cycle.

If you are buying a used vehicle in Riverside County, the seller must provide proof of a passing smog check dated within the last 30 days. A dealer will handle this as part of the sale, but a private seller is responsible for obtaining it. If you buy a vehicle without a current smog check, you cannot register it until you pass one yourself.

New vehicles (current model year) are exempt from smog checks for the first four years of registration. After that, they follow the standard two-year cycle. Vehicles that are 1975 or older, or that run on diesel fuel and weigh more than 14,000 pounds, have different testing rules — check with your local DMV office or the Bureau of Automotive Repair for specifics on your vehicle type.

Finding a certified testing station in Riverside County

Only STAR-certified stations can perform smog checks in California. These stations are inspected and approved by the Bureau of Automotive Repair (BAR), a division of the California Department of Consumer Affairs. A STAR station displays a visible decal and maintains equipment that meets state standards.

To find a certified station near you, visit the Bureau of Automotive Repair's online station locator at bar.ca.gov, or search "STAR smog check stations near me" in your web browser. You can also call your local DMV office for a list. Many independent repair shops, chain automotive retailers, and dedicated smog check stations in Riverside County hold STAR certification.

Prices vary between stations but are capped by law — you should not pay more than $70 for a basic smog check. Some stations charge less. Call ahead to confirm the price and whether you need an appointment, as wait times can be long during peak registration renewal periods (typically late in each month).

What happens if your vehicle fails the smog check

If your vehicle fails, the testing station will provide you with a Smog Check Test Report that lists the specific emissions that exceeded the limit. Common failure reasons include a faulty oxygen sensor, a malfunctioning catalytic converter, a clogged air filter, or an illuminated Check Engine light.

You have 30 days from the test date to repair your vehicle and return for a retest. The retest fee is the same as the initial test ($30 to $70). You do not have to return to the same station — any STAR-certified station will accept your vehicle for a retest. Once you pass, the station submits the results to the DMV electronically, and you can proceed with registration.

If repairs are expensive and your vehicle is older, you may want to research the California Car Scrappage Program or other vehicle retirement programs, which offer incentives to remove high-polluting vehicles from the road. The South Coast Air Quality Management District (SCAQMD) website lists current programs available to Riverside County residents.

Understanding the Check Engine light and smog check

If your vehicle's Check Engine light is on, it will fail the smog check automatically, regardless of actual emissions levels. The light indicates that your vehicle's onboard diagnostic system has detected a problem — often a loose gas cap, a faulty sensor, or an emissions system malfunction.

Before you schedule a smog check, have the Check Engine light diagnosed. Many auto parts stores (including AutoZone and O'Reilly) will read your diagnostic trouble codes for free. Once you know what triggered the light, you can decide whether to repair it yourself, have a mechanic fix it, or seek a second opinion. After repair, the light should turn off within a few driving cycles, though you may need to clear the code manually or have a technician do it.

Do not ignore the Check Engine light hoping it will go away before your smog check. The testing station's equipment will detect the diagnostic code even if the light is not currently visible, and your vehicle will still fail.

Smog check exemptions and special cases

Certain vehicles are exempt from smog checks in California. These include vehicles that are model year 1975 or older (though they may have different testing requirements), electric vehicles, vehicles with a salvage title, and vehicles registered as non-operational. Motorcycles and motorized bicycles are also exempt, though they must still meet other registration requirements.

If you have a vehicle with a gross vehicle weight rating (GVWR) over 14,000 pounds, or a diesel vehicle, different rules explore. Contact the Bureau of Automotive Repair or your local DMV office to confirm whether your vehicle needs a smog check and what type of test is required.

If you believe your vehicle should be exempt, bring your registration documents and vehicle identification number (VIN) to your local DMV office. Staff can confirm your vehicle's status and explain what steps you need to take for registration.

Smog check and vehicle registration timing

You can obtain a smog check up to 30 days before your registration expires. The test date becomes your new baseline for the two-year cycle, so timing your test strategically can align your smog check and registration renewal. For example, if your registration expires in March, you can test in February and your next test will not be due until February of the following even-numbered year.

Once you pass the smog check, the testing station electronically submits the results to the DMV. You can then renew your registration online through the DMV website, by mail, or in person at a DMV office. You do not need to bring the smog check paperwork to the DMV — the agency receives the results directly from the testing station.

If you renew your registration before obtaining a smog check, the DMV will flag your account and may suspend your registration. Always obtain a passing smog check before or when ready after renewing your registration to avoid delays or penalties.

Frequently Asked Questions

Can I get a smog check waiver if my vehicle is too old or broken to repair?

California offers a Referee Program for vehicles that fail smog checks and the repairs would cost more than a certain threshold (typically $500 to $800, depending on the vehicle). A Referee station can issue a waiver allowing you to register the vehicle for one year while you save for repairs. Contact the Bureau of Automotive Repair or your local DMV office to find a Referee station and learn the exact cost threshold for your vehicle.

What if I move out of Riverside County — do I still need a smog check?

If you move to another California air district, your vehicle will still need a smog check on the same two-year schedule, though the testing frequency or standards may differ slightly. If you move out of California entirely, you will no longer need a California smog check, but you may need to meet your new state's emissions requirements. Check with your new state's DMV or environmental agency.

How long does a smog check take?

The actual test takes 10 to 15 minutes. However, wait times at testing stations can range from 30 minutes to several hours depending on the time of day and time of month. Call ahead or visit during off-peak hours (early morning or mid-week) to minimize wait time. Peak periods are typically the last week of each month when registrations are expiring.

Can I test my vehicle in a different county and use the results in Riverside County?

Yes. A smog check from any STAR-certified station in California is valid statewide. If you travel to another county or region, you can test there and use the results for Riverside County registration. The testing standards are the same throughout California, so the results transfer without issue.

What documents do I need to bring for a smog check?

Bring your vehicle registration or proof of ownership and a valid photo ID. The testing station will record your vehicle identification number (VIN) and license plate. You do not need to bring your smog check paperwork from your last test — the station will look up your history electronically.