Ontario's Smog Check Requirements and Your Vehicle

Ontario, California follows the same smog check program as the rest of San Bernardino County. Your vehicle needs a smog check if you're registering it for the first time in California, renewing registration after it's expired for more than four months, or transferring ownership. Vehicles model year 1975 and newer are subject to the test, though some newer hybrids and electric vehicles may be exempt depending on their year.

The test itself measures your vehicle's exhaust emissions — primarily nitrogen oxides, particulate matter, and hydrocarbons — to confirm it meets California's standards. You cannot register or renew your vehicle's registration without a passing smog check report, and the Department of Motor Vehicles (DMV) will not process your paperwork without it.

Key Takeaways

  • Ontario residents must obtain a smog check from a California-certified testing station before registering or renewing a vehicle registration with the DMV.
  • The test costs between $30 and $70 depending on the testing station, and results are valid for 30 days from the test date.
  • You can find certified smog stations through the Bureau of Automotive Repair's online station locator or by searching for "smog check" and your zip code.
  • If your vehicle fails, you have 30 days to repair it and retest at no additional charge at the same station.
  • Diesel vehicles, motorcycles, and vehicles over 14,000 pounds have different testing requirements or may be exempt entirely.

Finding a Certified Smog Check Station in Ontario

You must use a station certified by California's Bureau of Automotive Repair (BAR). Not every mechanic or service center can perform smog checks — only stations that have passed BAR inspection and maintain current certification can issue valid test results. The BAR maintains an online station locator at bar.ca.gov where you can search by zip code or city name to find stations near you in Ontario.

When you call ahead, ask about wait times and whether you need an appointment. Many stations accept walk-ins, but calling first saves time, especially during peak registration periods. Confirm the station's hours and whether they accept the payment method you plan to use.

What Happens During the Smog Check Test

The test takes 10 to 30 minutes depending on your vehicle's age and type. For most gasoline vehicles, the technician will connect a probe to your vehicle's tailpipe and measure emissions while the engine idles and runs at a higher speed. The machine records whether your vehicle's emissions fall within California's limits for your vehicle's model year.

Bring your vehicle registration or proof of ownership and a valid photo ID. The technician will record your vehicle's identification number (VIN), mileage, and license plate. If your vehicle passes, you receive a smog check certificate (also called a "pass" or "STAR" report) that you present to the DMV when you register or renew. If it fails, the station provides a detailed report showing which emissions exceeded limits.

Cost and How Long Results Stay Valid

Smog check fees range from $30 to $70 depending on the station and your vehicle type. Diesel vehicles and vehicles with special equipment may cost more. The test result is valid for 30 days from the test date, so plan your DMV visit accordingly — if you wait longer than 30 days, you'll need a new test.

If your vehicle fails the initial test, you can retest at the same station within 30 days at no charge. This gives you time to have repairs made and confirm they fixed the problem. After 30 days, if you haven't retested, you must pay for a new smog check.

What to Do If Your Vehicle Fails the Smog Check

A failed smog check report tells you which emissions are too high — typically nitrogen oxides, hydrocarbons, or particulate matter. Common causes include a faulty oxygen sensor, a clogged air filter, worn spark plugs, or a malfunctioning catalytic converter. The report may suggest the type of repair needed, though it won't diagnose the exact problem.

Take the failed report to a repair shop and discuss what repairs might bring your vehicle into compliance. You don't have to use the same station for repairs. Once repairs are complete, return to the original smog check station for a retest within 30 days — the retest is free. If you retest after 30 days, you'll pay the full fee again.

Vehicles Exempt or Subject to Different Rules

Motorcycles, vehicles over 14,000 pounds, and some newer electric or hybrid vehicles have different requirements. Motorcycles registered in California do not require smog checks. Diesel vehicles and vehicles with gross vehicle weight ratings over 14,000 pounds follow a separate diesel smog check program with different testing procedures.

Some vehicles model year 2015 and newer may be exempt depending on their fuel type and certification status. Check your vehicle's registration documents or contact the BAR directly if you're unsure whether your vehicle needs a smog check. The DMV will also tell you during the registration process if a smog check is required.

Registering Your Vehicle After Passing the Smog Check

Once you have a passing smog check certificate, you can register or renew your vehicle with the DMV. You can do this online at dmv.ca.gov, by mail, or in person at an Ontario DMV office. The smog check result is transmitted electronically to the DMV by the testing station, so you may not need to bring the physical certificate — but bring it anyway in case there's a delay in the electronic transmission.

If you're registering a vehicle for the first time in California, you'll also need proof of ownership, a bill of sale or title, proof of California insurance, and payment for registration fees. The DMV will not process your registration without a passing smog check on file.

Frequently Asked Questions

Can I get a smog check waiver if my vehicle is old or has high mileage?

California does not issue smog check waivers based on age or mileage alone. However, if your vehicle fails the test twice in a row and you've spent $500 or more on repairs, you may be may be able to access for a referee smog check at a BAR-certified referee station, which has different testing standards. Contact the BAR or your local smog station for details on the repair cost waiver program.

What if the smog station says my vehicle can't be tested?

Some vehicles cannot be tested because they're too damaged, have missing equipment, or are not in safe operating condition. The station must provide a written reason. You can take the vehicle to a BAR referee station for a second opinion, or have repairs made and return to a regular station. A referee station can sometimes test vehicles that regular stations cannot.

Do I need a smog check if I'm just renewing my registration online?

Yes, if your registration is current and not expired, you may be able to renew online without a new smog check — but only if your vehicle passed a smog check within the required timeframe for your vehicle type. If your registration has been expired for more than four months, you'll need a new smog check before the DMV will process your renewal.

How long does it take to get smog check results?

You receive your results when ready after the test is complete. The station prints or emails your certificate right away. The results are also transmitted electronically to the DMV, though this transmission can take a few hours to a day. You don't need to wait for the electronic transmission to visit the DMV — bring your certificate with you.

Can I use a smog check from another county in California?

Yes, a smog check from any California-certified station is valid statewide. If you had your vehicle tested in another county, you can use that result to register in Ontario as long as the test is still within the 30-day validity window and your vehicle hasn't changed significantly.