Four Corners Service

Yes. Four Corners 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.

Yes. Four Corners Service is licensed as a Test Only smog station. This station performs the smog test and issues the certificate. It does not do repairs, so a failed vehicle has to be fixed elsewhere and brought back.

Four Corners Service is open Monday 8:30 AM to 5 PM; Tuesday 8:30 AM to 5 PM; Wednesday 8:30 AM to 5 PM; Thursday 8:30 AM to 5 PM; Friday 8:30 AM to 5 PM; Saturday 8:30 AM to 12 PM. Closed Sunday. Hours can change on holidays, so call ahead if you are cutting it close.

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

Four Corners Service accepts Cash, Credit Card.

Four Corners Service has held a BAR smog license since 2023. You can verify the license status at bar.ca.gov.

Four Corners 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 (707) 938-4176 for a quote.

Four Corners Service does not take online bookings here, but walk-ins are welcome. Call (707) 938-4176 to check the wait.

Staff at Four Corners 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.

Four Corners Service is a Test Only station, so it cannot do the repair. You would have the work done at a repair shop, then come back for the free retest within 30 days. California's Consumer Assistance Program covers up to $1,200 of emissions repairs for qualifying owners.

The closest alternatives in Sonoma are Broadway Shell Of Sonoma (1.0 mi) and Sonoma 76 (1.1 mi). Both are listed further up this page with their ratings and hours.