Why did my car fail a California smog check?
The most common reasons are a check engine light that's on, "readiness monitors" that haven't finished their self-tests (often after a battery change or cleared codes), high emissions readings from a misfire, sensor or worn catalytic converter, or a missing or modified emissions part. Your Vehicle Inspection Report says which. Get the cause diagnosed and repaired, drive the car normally until the monitors complete, then retest.
The usual reasons
| Reason on the report | What's behind it |
|---|---|
| Check engine light on, or codes stored | Any emissions-related fault, from an EVAP leak to a bad sensor |
| Readiness monitors incomplete | Battery recently disconnected, codes recently cleared, or an underlying fault preventing a test |
| High HC, CO or NOx | Misfires, a rich or lean mixture, EGR problems, a worn catalytic converter |
| Visual inspection failure | Missing, modified or non-CARB-approved emissions parts, vacuum hoses disconnected |
| Functional failure | Gas cap leak, check engine light not working |
What to do
- Read your Vehicle Inspection Report. It lists exactly what failed.
- Don't clear codes or disconnect the battery to "reset" it. That resets the monitors too.
- Get it diagnosed. The code points to a system; testing finds the part.
- Drive normally after the repair until the monitors complete.
- Retest. Some stations offer a reduced-cost retest within a set period; ask.
Hybrids and older cars
Hybrids like the Prius fail for many of the same reasons, and the engine runs less, so monitors can take longer to complete. Older cars are more likely to fail on emissions readings from worn parts. Either way, finding the actual cause is what gets it passing. Smog repair
From drivers who came to us
I had my 2009 prius "check engine" light on that somehow caused smog test failing… The check engine light issues were fixed. Smog test was passed.
I called early morning to see if they could fit me into their schedule to fix something to pass smog. Pulled up later that day and got me out of there within a half hour.
Had an issue getting my car smog certified. Problem solved - and they went above & beyond, in every way.
Transmission was acting up we did not think it would pass smog… it did pass smog and gets better Gas mileage now so happy we took it there
Excerpts from verified customer reviews on Yelp.
More questions
How often does my car need a smog check in California?
Most gasoline vehicles need one every two years once they're more than eight model years old, and at change of ownership if more than four model years old. There are exceptions, including electric vehicles. Your DMV renewal notice will say if it's required.
What are readiness monitors?
Self-tests the car's computer runs on its emissions systems. If too many are incomplete, the car can't pass. They complete after a mix of driving, often a few days of normal city and highway use.
What is a STAR station?
A smog station that meets higher performance standards set by the state. Some vehicles are directed to STAR stations; your DMV renewal notice will tell you.
Is there financial help for smog repairs?
California's Bureau of Automotive Repair offers a Consumer Assistance Program for eligible owners. Check the BAR website for current rules.