Smog check in Walnut, CA

Stations in Walnut set their own prices, and prices change, so call ahead or bring a coupon. One Walnut station currently lists a $50.75 smog check coupon. Check each coupon's fine print for which vehicles it covers and whether the certificate fee is included. The Bureau of Automotive Repair puts the statewide average at $69.16 (August 2026): about $65 for a 2000-or-newer vehicle and $73 for 1999-or-older, plus the $8.25 state certificate when the vehicle passes.

In most of California, gasoline vehicles more than eight model years old need a smog check every two years when the registration is renewed, and most vehicles need one when they change owners. A few rural areas only require it on a change of ownership. Your DMV renewal notice says whether this year’s renewal needs one.

Yes. All 5 stations in Walnut are STAR certified. You only need one if your DMV renewal notice says the vehicle must be tested at a STAR station.

Walnut has 2 test-and-repair shops and 3 test-only stations. A test-only station inspects and certifies but does not repair, so a failed vehicle is fixed elsewhere and brought back. A test-and-repair shop can test, diagnose and repair in one place. Both issue the same state certificate.

Bring the vehicle and its registration or DMV renewal notice. Make sure the check engine light is off before you go; on a 2000-or-newer vehicle an illuminated check engine light is an automatic fail.

The vehicle has to be repaired and pass a retest before the DMV renews the registration. Retest pricing is set by each station, so ask before the first test. Income-eligible owners can apply to BAR’s Consumer Assistance Program for repair assistance or vehicle retirement.

A passing smog check is sent to the DMV electronically and is valid for 90 days, so get it done within 90 days of renewing or selling the vehicle.