Smog check failure repair in San Mateo

Why cars fail smog

California's smog check looks at more than the tailpipe. On most cars built since 1996, the inspector reads the car's onboard computer. You can fail for:

• A check engine light that's on, or stored emissions codes
• Incomplete readiness monitors: the car hasn't finished its self-tests, often because the battery was recently disconnected or codes were just cleared
• High emissions readings, from misfires, a worn catalytic converter or a faulty sensor
• Visual or functional failures: missing or modified emissions parts, or a leaking gas cap

How we fix it

We read your smog report, scan the car, and test to find the actual cause, whether that's an oxygen sensor, an EVAP leak, a misfire or a converter. After the repair, the car needs to complete its readiness self-tests, which takes a mix of city and highway driving. We'll tell you how to drive it, or do the drive cycle ourselves, so you don't go back for the test before it's ready.

Don't clear the codes right before a smog check. Clearing codes also resets the readiness monitors, which guarantees a failed or rejected test until they complete again.

Common smog-failure repairs

Oxygen and air-fuel sensors, EVAP system leaks and purge valves, gas caps, misfires (spark plugs, coils, injectors), EGR systems, and catalytic converters. On hybrids like the Prius, warning lights from the hybrid or emissions system are a common cause too.