Clean Truck Check testers in Modesto, CA

23 testing businesses in Modesto are on CARB's public Clean Truck Check tester list (24 credentialed testers). 21 offer mobile testing at your yard, 11 can do smoke opacity tests for older non-OBD trucks and 17 test motorhomes. Counting nearby cities, 83 listings are within 20 miles.

Testers in Modesto

More testers within 20 miles of Modesto

Trucking in Modesto: what to know

Modesto sits on SR-99 in Stanislaus County, with food-processing and agricultural trucking. Agricultural vehicles test once a year.

Stanislaus County (Modesto, Turlock, Ceres) has many food-processing and agricultural fleets on SR-99.

What a Clean Truck Check costs in Modesto

Testers set their own prices and most do not publish them. Across the California prices we found, an OBD test usually costs $50–$135 per vehicle and a smoke opacity test $190–$200. Mobile testers in Modesto may add a trip fee but often discount fleets that test several trucks at once. How prices compare.

Frequently asked questions

How many Clean Truck Check testers are in Modesto?

CTC Finder lists 23 testing businesses in Modesto from CARB's public tester list (24 credentialed testers), last checked November 1, 2026. Listing on CARB's list is optional, so the real number can be higher.

Is there mobile Clean Truck Check testing in Modesto?

Yes. 21 listed businesses in Modesto offer mobile testing, which means the tester comes to your yard. Use the Mobile filter above to see them.

How much does a Clean Truck Check test cost in Modesto?

Testers set their own prices. Published prices for an OBD test are usually $50–$135 per vehicle; smoke opacity tests for older trucks often cost more, and mobile testers may add a trip fee. See the cost guide.

How often does my truck need a Clean Truck Check test?

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.

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.