Clayton Auto Service

Yes. Clayton Auto Service is STAR certified with the California Bureau of Automotive Repair, so it can test vehicles the DMV directs to a STAR station, including gross polluters.

No. Clayton Auto Service is licensed as a Test & Repair station. This station can run your smog test and, if the vehicle fails, diagnose and repair it in the same shop.

Clayton Auto Service is open Monday 8:30 AM to 6 PM; Tuesday 8:30 AM to 7 PM; Wednesday 8:30 AM to 7 PM; Thursday 8:30 AM to 7 PM; Friday 8:30 AM to 7 PM; Saturday 8:30 AM to 7 PM. Closed Sunday. Hours can change on holidays, so call ahead if you are cutting it close.

Yes. Clayton Auto Service accepts walk-ins, so you can drive in without booking ahead.

Clayton Auto Service accepts Credit Card, Debit Card, NFC/Contactless.

Google lists the following accessibility features at Clayton Auto Service: wheelchair accessible entrance, wheelchair accessible parking, wheelchair accessible restroom.

Clayton Auto Service has held a BAR smog license since 2017. You can verify the license status at bar.ca.gov.

Clayton Auto Service has not published a price on SmogCheckDeals. The Bureau of Automotive Repair puts the statewide average at $69.16 as of August 2026, about $65 for a 2000-or-newer vehicle and $73 for 1999-or-older, plus the $8.25 certificate fee. Call (925) 686-1000 for a quote.

Clayton Auto Service does not take online bookings here, but walk-ins are welcome. Call (925) 686-1000 to check the wait.

Staff at Clayton Auto Service speak English.

Bring the car, your registration or DMV renewal notice, and a way to pay. Most smog checks take 15 to 30 minutes, and most visits are closer to 20.

Because Clayton Auto Service is a Test & Repair station, it can diagnose and repair the problem in the same shop, then run the free retest within 30 days. If the repair bill is steep, California's Consumer Assistance Program covers up to $1,200 of emissions repairs for qualifying owners.

The closest alternatives in Concord are Green Star Smog (2.7 mi) and Bayside Smog Llc (2.8 mi). Both are listed further up this page with their ratings and hours.