Why Did My Car Fail Smog? Causes and Fixes for Redding Drivers
Pass Your Smog Check Without the Stress
A failed smog test has a specific cause, and the test report tells us where to start. We diagnose it, fix it, and get your car ready to retest.
Usually safe to drive while you get it fixed, but you can't renew your registration until it passes, so book early.
Why did my car fail smog? The most common reasons are a check engine light that's on, which is an automatic fail in California, a failing oxygen sensor or catalytic converter, an evaporative emissions leak, misfires, exhaust leaks, or system monitors that aren't ready yet.
California requires a smog check every two years for most vehicles, and a car with the check engine light on will fail automatically. Bring us your failed test report: it shows which readings were out of range.
Common reasons cars fail smog
- The check engine light is on. An automatic fail. See check engine light is on.
- A failing oxygen sensor or catalytic converter. Emissions repair
- An evaporative emissions leak. Sometimes as simple as the gas cap.
- Misfires or a rich fuel mixture. See rough idle or misfire. Engine diagnostics
- Exhaust leaks. Exhaust system repair
- Monitors not ready. Common after a battery replacement or cleared codes; the car needs to be driven before it can pass.
Failed, or have a test coming up?
Book an emissions diagnosis and bring your smog report.
How we find the cause and fix it
- We review your smog report and scan for codes.
- We test the systems tied to the failed readings.
- You get an estimate before we start, so there are no surprises.
- After the repair, we make sure the system monitors are ready before you retest.
Get ready to retest.
Book an emissions repair with an estimate before any work.
Is it safe to keep driving?
Usually, yes, as long as the car runs normally. But you can't renew your registration until it passes, so book early. If the check engine light is flashing or the car runs rough, stop driving and call us.
Services we offer that could fix your problem
We confirm the cause first, then recommend only the repair you need.
- Emissions RepairPass Your Smog Check Without the StressLearn more
- Check Engine LightFind Out Exactly Why Your Check Engine Light Is OnLearn more
- Engine DiagnosticsGet a Clear Answer About What's Wrong With Your EngineLearn more
- Exhaust System ServiceQuiet a Loud Exhaust and Cut Harmful EmissionsLearn more
Common questions
Why Did My Car Fail Smog?
The most common reasons are a check engine light that's on, which is an automatic fail in California, a failing oxygen sensor or catalytic converter, an evaporative emissions leak, misfires, exhaust leaks, or system monitors that aren't ready yet.
Will my car fail smog with the check engine light on?
Yes. In California, an illuminated check engine light is an automatic fail.
Why does my car say monitors not ready?
The monitors reset after a battery disconnect or cleared codes. The car needs a mix of normal driving before they're ready.
Do you do smog checks?
We diagnose and repair the causes of a failed smog check and get your car ready to pass the retest.