A1 Stop Smog
Clean Truck Check tester in Antioch, CA (Contra Costa County).
- OBD test
- Motorhomes
A1 Stop Smog appears on CARB's public list of credentialed Clean Truck Check testers. It lists OBD testing, motorhome testing.
- Location
- 1810 Verne Roberts Cir, Antioch, CA 94509
- County
- Contra Costa County
- Phone
- (925) 445-7875
- Mobile testing
- No (test at the shop)
- OBD testing
- Yes
- Smoke opacity (non-OBD)
- No
- Motorhomes
- Yes
- Credentialed testers
- 1
- Last verified
Call (925) 445-7875 Open in Google Maps
Before you call
- Have your VIN, odometer reading and plate number ready.
- Your vehicle must be registered in CTC-VIS and the annual compliance fee paid; the tester submits the result to CARB.
- Ask for the price per vehicle. Typical published prices for an OBD test are $50–$135 per vehicle (see cost guide).
Which trucks A1 Stop Smog can test
The test CARB requires depends on the engine's fuel and model year. Based on the services A1 Stop Smog lists on CARB's tester list:
| Your vehicle | Test required | This tester |
|---|---|---|
| Diesel, model year 2013 or newer | OBD scan | Yes |
| Alternative fuel (natural gas, propane), 2018 or newer | OBD scan | Yes |
| Diesel, model year 2012 or older (no OBD) | Smoke opacity test (SAE J1667) plus visual inspection | Not listed |
| California-registered motorhome | Same test as above by engine year, once a year | Yes |
For a 2012 or older diesel, the nearest listed tester with smoke opacity testing is Contra Costa Mobile Repair in Antioch, about 1 mile away. See listing.
If you need a tester at your yard, the nearest listed tester that offers mobile testing is Charlotte Larsen in Antioch, about 1 mile away. See listing.
Clean Truck Check testers in Contra Costa County
A1 Stop Smog is one of 61 testing businesses in Contra Costa County on CARB's public tester list. 57 of them offer mobile testing and 38 do smoke opacity tests. In Antioch itself there are 11 listed businesses, 10 of them mobile. All testers in Contra Costa County.
When your truck is due
Most trucks test twice a year, on a schedule tied to the DMV registration expiration date. CARB says OBD trucks move to four tests a year beginning October 2027. California-registered (non-commercial) motorhomes and agricultural vehicles test once a year. See the deadline guide. You can test up to 90 days before a deadline. Get a free email reminder before each one.
How to check a tester's credential
CARB publishes its Clean Truck Check tester list, where A1 Stop Smog appears as of November 1, 2026. Listing there is optional, so a missing name does not always mean a tester is not credentialed. After the test, check that the passing result shows for your vehicle in CTC-VIS; that is what counts for compliance.
Frequently asked questions
Does A1 Stop Smog offer mobile Clean Truck Check testing?
Not according to CARB's tester list; plan to bring the truck to the tester. The nearest listed mobile tester is Charlotte Larsen (about 1 mile).
Can A1 Stop Smog test a 2012 or older diesel truck?
A1 Stop Smog does not list smoke opacity testing, which older non-OBD diesel trucks need. The nearest listed tester that does is Contra Costa Mobile Repair (about 1 mile). Trucks from 2013 on get an OBD scan instead.
How much does A1 Stop Smog charge for a Clean Truck Check?
A1 Stop Smog has not published prices with us; call (925) 445-7875 for a quote. Published California prices are usually $50–$135 per vehicle for an OBD test and $190–$200 for a smoke opacity test, plus CARB's annual fee ($32.13 in 2026). See the cost guide.
Is A1 Stop Smog a CARB-credentialed tester?
A1 Stop Smog appears on CARB's public Clean Truck Check tester list, last checked November 1, 2026. Only credentialed testers can submit results to CARB; after the test, confirm the passing result shows for your vehicle in CTC-VIS.
Other testers near Antioch
-
Charlotte Larsen
- Mobile testing
- OBD test
- Motorhomes
-
Contra Costa Mobile Repair
- Mobile testing
- OBD test
- Smoke opacity
- Motorhomes
-
Drill Tech Drilling Shoring Inc.
- Mobile testing
- OBD test
- Smoke opacity
- Motorhomes
-
Habibullah Nazari
- Mobile testing
- OBD test
- Smoke opacity
- Motorhomes
-
Miguel Rodriguez
- Mobile testing
- OBD test
- Smoke opacity
- Motorhomes
-
Mobile Golden State Emissions Testing Antioch
- Mobile testing
- OBD test
- Smoke opacity
- Motorhomes
Source: CARB's public Clean Truck Check tester list, last checked . Listing on CARB's list is optional for testers, so some credentialed testers are not shown. Services, hours and prices change; please confirm with the tester before you go. Something wrong? Send a correction.