Failing a smog check can be frustrating—especially when your vehicle seems to be running just fine. But don't worry, a failed test doesn't mean you're stuck. In most cases, you can have the problem repaired and your vehicle retested, often without much delay. The key is knowing what caused the failure and how to fix it the right way.
If your car didn’t pass inspection, here’s what you should do next.
Understanding Why Your Vehicle Failed
When your car doesn’t pass a smog check, it’s usually due to high emissions, incomplete system readiness, or a malfunction indicated by the check engine light. In California, even minor issues—like a loose gas cap or faulty sensor—can trigger a failure.
Your test results should include a report showing what part of the system didn’t meet standards. This might point to an issue with your catalytic converter, oxygen sensors, evaporative emissions system, or another component. If you’re not sure how to read the report, a qualified repair shop can explain what it means and what needs to be fixed.
Yes—You Can Absolutely Retest
After repairs are made, your vehicle can be retested. In fact, California’s smog program is designed with this process in mind. Many certified test-and-repair stations, including those authorized by the Bureau of Automotive Repair (BAR), offer repair services along with retesting, so you can take care of both steps in one place.
In most cases, your retest will only include the sections you previously failed—so you’re not starting from scratch.
Common Repairs That Help You Pass
- Replacing oxygen or air-fuel ratio sensors
- Repairing EVAP leaks or faulty purge valves
- Replacing a worn catalytic converter
- Fixing misfires by replacing spark plugs or coils
- Resetting or replacing faulty emission-related sensors
If your check engine light was on during the test, resolving that issue alone may be enough to pass the second time.
Let the System Relearn After Repairs
After repairs are completed, your vehicle may need to complete a few “drive cycles” before it’s ready to retest. This is because the car’s onboard computer system needs time to monitor all systems and confirm the problem is truly resolved.
Depending on your make and model, this may require driving under specific conditions for a certain amount of time. Your repair shop can guide you on whether your car is ready to return for testing.
The Importance of Certified Repairs
To ensure your vehicle passes and that the state recognizes the repairs, it’s best to go to a shop that’s certified to perform smog-related repairs. These shops understand California’s emissions standards and know how to make sure everything is done properly, from diagnostics to final testing.
Even if your car requires a waiver or additional paperwork, a qualified shop can help you through the process smoothly.
Morin Brothers Automotive – Certified Smog Repair and Retest in San Luis Obispo, CA
At Morin Brothers Automotive in San Luis Obispo, CA, we help drivers who didn’t pass their smog test get back on the road. From emissions diagnostics to certified repairs and retesting, our experienced team will guide you every step of the way. Don’t let a failed smog test slow you down—schedule your repair and retest with us today.