A 1 rating means your vehicle passed the smog check with flying colors

A 1 rating on a California smog check is the best possible result. It means your vehicle's emissions are well below the state's limits and you have no restrictions on registration or driving. You can renew your registration normally and do not need to return for another smog check until your next renewal cycle (typically every two years for most vehicles).

The rating system uses numbers 0, 1, and 2. A 1 means you passed cleanly. A 0 means you failed and cannot register. A 2 means you passed but are flagged for a second test in 30 days to confirm the results were not a fluke. Getting a 1 is the outcome you want.

Key Takeaways

  • A 1 rating means you passed the smog check and your vehicle's emissions are within California's legal limits.
  • You can register your vehicle normally with a 1 rating and do not need to retest until your next scheduled smog check.
  • A 1 rating is issued by the test station and printed on your smog certificate, which you present to the DMV or use for online registration.
  • If you received a 2 rating instead, you must return within 30 days for a retest to confirm your vehicle still meets standards.

How the smog check rating system works

California's Bureau of Automotive Repair (BAR) oversees smog testing and uses a three-point scale. The rating reflects how your vehicle performed against state emission standards, not just whether it passed or failed.

A 1 rating means your emissions test results fell within the acceptable range. The test measures nitrogen oxides (NOx), carbon monoxide (CO), and hydrocarbons (HC) depending on your vehicle's year and type. When all measurements come back within limits, you get a 1. A 2 rating means you passed but were close enough to the limit that the station flags you for a retest. A 0 means you failed and your vehicle does not meet standards.

What you need to do after getting a 1 rating

Take your smog certificate to the DMV or use it to renew your registration online if your state allows it. The certificate shows your vehicle identification number (VIN), the test date, and the 1 rating. The DMV will not ask for anything else related to emissions.

Keep a copy of your smog certificate for your records. You will not need it again until your next smog check is due, which is usually two years later for passenger vehicles. Some vehicles (those over 16 years old, diesel vehicles, and certain other types) may have different testing schedules, so check your registration renewal notice.

Why some vehicles get a 2 rating instead

A 2 rating does not mean you failed. It means you passed, but your emissions were close enough to the state limit that the test station wants confirmation. This can happen if your vehicle is older, has higher mileage, or is running slightly rich or lean.

If you get a 2, you must return to a smog station within 30 days for a retest at no additional cost (the original test fee covers both). Most vehicles that get a 2 on the first test will get a 1 on the second test. If you get another 2 or a 0 on the retest, you will need to repair your vehicle and test again.

The difference between a 1 rating and passing with repairs

A 1 rating means you passed without needing any work done to your vehicle. Some vehicles fail their first test (get a 0) but pass after repairs. Once repaired and retested, they receive either a 1 or a 2, depending on how close they are to the limits.

If your vehicle failed before, keep records of what was repaired. This can help a mechanic diagnose future issues faster. A 1 rating after repairs is just as valid as a 1 rating on the first try — both allow you to register normally.

What happens if you lose your smog certificate

You can request a duplicate from the smog station where you tested. Bring your vehicle registration and identification. The station can print another copy of your certificate showing the same 1 rating.

If the station is no longer in business or you cannot locate it, contact the Bureau of Automotive Repair at (916) 445-6328 or visit their website. They can look up your test results by VIN and issue a replacement certificate. This process may take a few days.

Frequently Asked Questions

Does a 1 rating mean my vehicle will never fail a smog check?

No. A 1 rating is valid for your current test, but your vehicle's condition can change. Engine wear, a failing oxygen sensor, or a loose gas cap can cause problems by your next test. A 1 today does not may provide a 1 in two years.

Can I register my vehicle online with a 1 rating?

Yes, if your state allows online registration. You will need your smog certificate number or can upload an image of the certificate. Check your DMV's website for the exact process in your area.

What if the test station made a mistake and gave me a 1 when I should have failed?

Contact the Bureau of Automotive Repair to report your concern. They can review the test results and the station's equipment calibration. If an error is found, BAR can issue a corrected certificate or require a retest.

Do I need to bring my smog certificate to the DMV in person?

Not always. Many DMVs accept smog certificates by mail or online upload. Some still require in-person submission. Check your local DMV's website or call ahead to confirm what they accept.