What Smog Check requires in Riverside

Riverside County requires a smog check (also called an emissions test) every two years for most vehicles, or every year if your car is model year 1975 or older. You need to pass before you can renew your vehicle registration with the California Department of Motor Vehicles. The test measures what comes out of your tailpipe — carbon monoxide, nitrogen oxides, and particulate matter — to confirm your vehicle meets state air quality standards.

You can get tested at any STAR station (Smog Test And Repair) in Riverside County. These are certified testing facilities run by mechanics, service stations, and dedicated smog shops. The test itself takes about 10 to 15 minutes and costs between $30 and $70, depending on the station and your vehicle type. You do not have to test at the dealership where you bought the car, and you do not have to repair there if you fail — you can take your results anywhere.

Your vehicle is exempt from smog check if it is model year 2000 or newer and has been registered in California for less than eight years, or if it is a zero-emission vehicle like a plug-in hybrid or electric car. Diesel vehicles, motorcycles, and vehicles registered as non-operational also have different rules. Check the California Bureau of Automotive Repair website or call your local Riverside County DMV office to confirm your vehicle's status before you pay for a test.

Key Takeaways

  • Riverside County requires smog checks every two years for most vehicles, and you cannot renew your registration without a passing result.
  • Any STAR station in the county can test your vehicle; the test takes 10 to 15 minutes and costs $30 to $70.
  • Newer vehicles (model year 2000 and up, registered in California less than eight years) are exempt from testing.
  • If you fail, you have 30 days to repair and retest at no additional charge at the same station, or you can take your vehicle elsewhere.
  • You can test up to 60 days before your registration expires, so plan ahead to avoid late fees.

Finding a STAR station near you

The California Bureau of Automotive Repair maintains a searchable list of all certified STAR stations on its website at bar.ca.gov. Enter your ZIP code or city name to see stations in Riverside County, their hours, phone numbers, and what types of vehicles they test. Many stations accept walk-ins, but calling ahead can save you a wait, especially during peak times like the end of the month.

Independent smog shops often have shorter wait times than busy service stations or dealerships. Look for stations that display the official STAR certificate in the window — this means they have passed state inspection and follow testing rules. Read recent reviews on Google or Yelp to see what other drivers report about wait times, pricing, and whether the staff explained results clearly.

What happens during the test

When you arrive, bring your vehicle registration and proof of current insurance. The technician will connect a probe to your tailpipe and run your engine through a standardized cycle that simulates city and highway driving. For vehicles model year 1996 and newer, the test also reads your vehicle's onboard diagnostic system — a computer that monitors emissions equipment. The whole process takes 10 to 15 minutes.

You will receive a printed result when ready. If you pass, the station sends your result electronically to the DMV, and you can renew your registration online or at a DMV office. If you fail, the result shows which pollutants exceeded the limit. You then have 30 days to repair the problem and return to the same station for a free retest. If you pass the retest, that result is reported to the DMV.

What to do if you fail the smog check

A failed smog check usually means your vehicle has an emissions problem — a faulty oxygen sensor, a loose gas cap, a clogged catalytic converter, or a check engine light that has been ignored. The test result will tell you which emissions system is the issue, but not always the exact repair needed. You can take the result to any mechanic, not just the station that tested you.

Before you spend money on repairs, ask a mechanic to read your vehicle's diagnostic codes — this costs $50 to $100 and tells you what is actually broken. Some repairs are straightforward (a new gas cap costs $15; clearing a code and retesting costs nothing). Others are expensive (a catalytic converter replacement can run $500 to $2,500). If the repair cost is very high, get a second opinion from another shop.

Once you repair the vehicle, return to the same STAR station for a free retest within 30 days. If you pass, you are done. If you fail again, you can retest once more at no charge. After two failed retests, you must wait 30 days before testing again at a different station.

Timing your smog check around registration renewal

You can test up to 60 days before your registration expires. Testing early gives you time to repair and retest if you fail, without rushing. Your registration expiration date is printed on your vehicle registration card — check it now so you know your important date.

If your registration has already expired, you cannot legally drive the vehicle. Renew it as soon as possible, even if you have not yet passed smog check. You will need the passing test result to complete the renewal, so get tested when ready. Late registration renewal fees vary by county but typically add $50 to $200 to your renewal cost.

Common reasons for smog check failure in Riverside

Riverside's air quality challenges mean some vehicles fail more often than others. Older vehicles (pre-1996) are more likely to fail because their emissions systems are less precise. Vehicles with check engine lights almost always fail — the light itself indicates an emissions problem. Vehicles that are not regularly maintained, with old spark plugs, dirty air filters, or overdue oil changes, also fail more often.

A loose or missing gas cap is one of the easiest fixes and one of the most common reasons for failure. If your check engine light is on, do not ignore it — have the code read before you test. If you have recently had engine work done and the light came on afterward, return to the shop that did the work; they may have forgotten to clear the diagnostic code.

Frequently Asked Questions

Can I test my vehicle in a different county?

Yes. You can test anywhere in California, not just Riverside County. However, you must test in the county where your vehicle is registered within 60 days of your registration expiration date. If you move to another county, you will need to test in your new county for future renewals.

What if I just bought a used car in Riverside?

If the car passed smog check within the last 90 days, the seller should have given you a passing certificate — you can use that to register it. If it did not pass recently, or if you are unsure, get it tested before you complete the registration. Some dealers offer a smog check as part of the sale; ask before you buy.

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

If your vehicle is registered in Riverside County, yes — registration status determines the requirement, not how often you drive. The only exception is if you register your vehicle as non-operational (off the road), which requires a different process and prevents you from driving it legally.

What if the smog station made a mistake on my test?

If you believe the result is wrong, you can request a retest at a different STAR station. Bring your failed result with you. If the second station passes your vehicle, contact the California Bureau of Automotive Repair to report the first station. The BAR investigates stations that produce consistently inaccurate results.

How much does a smog check cost in Riverside?

The test itself costs $30 to $70 depending on the station and your vehicle type. Repairs, if needed, vary widely — a gas cap is $15, but a catalytic converter can cost $500 to $2,500. The retest after repair is free at the same station.