Smog check repair
California requires a smog check on most vehicles every two years, and again on transfer of ownership. Fail it and you cannot renew your registration until the car passes — which makes a failed test a deadline, not just a repair.
Bring the failure report with you. It states exactly why the car failed, and that tells us where to look instead of starting from scratch.
Common reasons cars fail
- Check engine light on — an automatic fail, whatever the emissions numbers say
- Readiness monitors not set, usually because codes were cleared recently
- A failing oxygen sensor or catalytic converter
- Evaporative system leaks — sometimes as simple as the fuel cap
- A worn ignition system causing a misfire
- Visual failures — missing or modified emissions equipment
How we approach it
- Read the failure report and the stored codes together
- Test the system that actually failed rather than replacing the obvious part
- Repair the fault and verify with live data
- Drive the car until the readiness monitors set
- Confirm it is ready before you pay for another test
The last step matters: a car repaired but not driven enough for its monitors to reset will fail again on a technicality. We tell you what we found and what it costs before we do the work. Nothing happens that you did not agree to.
Frequently asked questions
My check engine light is on but the car drives fine. Will it pass?
No. An illuminated check engine light is an automatic failure in California regardless of how the car runs.
Can I clear the codes before the test?
It will turn the light off, but it also resets the readiness monitors — and a car with unset monitors fails. It generally makes things worse.
Do you perform the smog test itself?
This page is about diagnosing and repairing the faults that cause a failure. Call us with what your report says and we will tell you what is involved.