--- title: "Clean Truck Check Testers in Napa, CA (11 listed)" description: "Find 11 CARB-credentialed Clean Truck Check testers in Napa, Napa County: 11 offer mobile testing, 6 do smoke opacity tests. Phone numbers, services and nearby…" url: "https://ctcfinder.com/testers/napa-county/napa/" updated: "2026-11-01" publisher: "CTC Finder (independent directory, not affiliated with CARB)" --- # Clean Truck Check testers in Napa, CA 11 testing businesses in Napa (Napa County) are on CARB's public Clean Truck Check tester list (12 credentialed testers). 11 offer mobile testing, 6 do smoke opacity tests, 8 test motorhomes. > CTC Finder is an independent directory, not affiliated with CARB. Tester data: CARB Clean Truck Check public tester list, last checked November 1, 2026. Confirm services, hours and prices with the tester. ## Testers in Napa - **[Precision Automotive Services](https://ctcfinder.com/tester/precision-automotive-services-napa/)** — 198 Soscol Ave, Napa, CA 94559 — (707) 912-9318. Services: mobile testing, OBD testing, motorhome testing. - **[Aaron Ramo](https://ctcfinder.com/tester/aaron-ramo-napa/)** — Napa, CA 94559 — (707) 225-7982. Services: mobile testing, OBD testing, smoke opacity (non-OBD) testing, motorhome testing. - **[Hector Kreitz](https://ctcfinder.com/tester/hector-kreitz-napa/)** — Napa, CA 94558 — (707) 704-9863. Services: mobile testing, OBD testing. - **[JB Mobile Service](https://ctcfinder.com/tester/jb-mobile-service-napa/)** — 787 Airpark Rd, Napa, CA 94558 — (707) 206-5358. Services: mobile testing, OBD testing, smoke opacity (non-OBD) testing. - **[Jones Family Mobile Diesel Repair](https://ctcfinder.com/tester/jones-family-mobile-diesel-repair-napa/)** — 933 Water St, Napa, CA 94559 — (410) 301-8518. Services: mobile testing, OBD testing, smoke opacity (non-OBD) testing, motorhome testing. - **[Mobile Testing](https://ctcfinder.com/tester/mobile-testing-napa/)** — Napa, CA 94559 — (916) 538-7777. Services: mobile testing, OBD testing, smoke opacity (non-OBD) testing, motorhome testing. - **[Napa Valley RV and Truck](https://ctcfinder.com/tester/napa-valley-rv-and-truck-napa/)** — 26 Big Leaf Ct, Napa, CA 94558 — (707) 850-6624. Services: mobile testing, OBD testing, motorhome testing. - **[Napa Valley Unified School District](https://ctcfinder.com/tester/napa-valley-unified-school-district-napa/)** — 1340 Menlo Ave, Napa, CA 94558 — (707) 492-0366. Services: mobile testing, OBD testing, smoke opacity (non-OBD) testing, motorhome testing. - **[Quick Smog](https://ctcfinder.com/tester/quick-smog-napa/)** — 662 Soscol Ave, Napa, CA 94559 — (707) 927-3956. Services: mobile testing, OBD testing, motorhome testing. - **[Steve DiPiero](https://ctcfinder.com/tester/steve-dipiero-napa/)** — Napa, CA 94559 — (707) 996-3685. Services: mobile testing, OBD testing, smoke opacity (non-OBD) testing. - **[Williams Transmissions and Express Smog](https://ctcfinder.com/tester/williams-transmissions-and-express-smog-napa/)** — 238 Soscol Ave, Napa, CA 94559 — (707) 310-1999. Services: mobile testing, OBD testing, motorhome testing. ## More testers within 20 miles - **[Ajmer Shergill](https://ctcfinder.com/tester/ajmer-shergill-fairfield/)** — Fairfield, CA 94534 — (707) 227-6194 — 9 mi. Services: mobile testing, OBD testing. - **[California CTC Mobile Testing](https://ctcfinder.com/tester/california-ctc-mobile-testing-fairfield/)** — 5328 Venus Dr, Fairfield, CA 94534 — (707) 761-4000 — 9 mi. Services: mobile testing, OBD testing, smoke opacity (non-OBD) testing, motorhome testing. - **[Chris Casilang](https://ctcfinder.com/tester/chris-casilang-fairfield/)** — Fairfield, CA 94534 — (707) 205-6922 — 9 mi. Services: OBD testing, smoke opacity (non-OBD) testing. - **[Elite Truck & trailer Repair LLC](https://ctcfinder.com/tester/elite-truck-and-trailer-repair-llc-fairfield/)** — 505 Watt Dr Suite 5, Fairfield, CA 94534 — (707) 310-9779 — 9 mi. Services: mobile testing, OBD testing, motorhome testing. - **[Golden State Emissions Pro](https://ctcfinder.com/tester/golden-state-emissions-pro-fairfield/)** — 4776 Opus Cir, Fairfield, CA 94534 — (707) 373-7897 — 9 mi. Services: mobile testing, OBD testing, motorhome testing. - **[Mobile Testing](https://ctcfinder.com/tester/mobile-testing-fairfield-2/)** — Fairfield, CA 94534 — (916) 538-7777 — 9 mi. Services: mobile testing, OBD testing, smoke opacity (non-OBD) testing, motorhome testing. - **[Sohal Truck & Tires](https://ctcfinder.com/tester/sohal-truck-and-tires-fairfield/)** — 393 Watt Dr, Fairfield, CA 94534 — (707) 208-3032 — 9 mi. Services: mobile testing, OBD testing, motorhome testing. - **[ECS Mobile Services](https://ctcfinder.com/tester/ecs-mobile-services-vallejo/)** — 179 Coloma Way, Vallejo, CA 94589 — (707) 398-8574 — 11 mi. Services: mobile testing, OBD testing, motorhome testing. - **[Michael's Transportation Service Inc.](https://ctcfinder.com/tester/michaels-transportation-service-inc-vallejo/)** — 140 Yolano Dr, Vallejo, CA 94589 — (707) 712-6713 — 11 mi. Services: not listed. - **[Carb Tester](https://ctcfinder.com/tester/carb-tester-sonoma/)** — 21707 8th St E, Sonoma, CA 95476 — (707) 772-9077 — 12 mi. Services: mobile testing, OBD testing, motorhome testing. - **[Faustino](https://ctcfinder.com/tester/faustino-sonoma/)** — 23195 Maffei Rd, Sonoma, CA 95476 — (707) 953-3466 — 12 mi. Services: mobile testing, smoke opacity (non-OBD) testing, motorhome testing. - **[Manzoni Inc](https://ctcfinder.com/tester/manzoni-inc-sonoma/)** — 27500 Skaggs Island Rd, Sonoma, CA 95476 — (707) 996-3685 — 12 mi. Services: mobile testing, OBD testing, smoke opacity (non-OBD) testing, motorhome testing. ## Cost Typical published prices in California: OBD test $50–$135 per vehicle; smoke opacity test $190–$200. Prices are set by each tester. ## Frequently asked questions ### How many Clean Truck Check testers are in Napa? CTC Finder lists 11 testing businesses in Napa from CARB's public tester list (12 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 Napa? Yes. 11 listed businesses in Napa 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 Napa? 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](https://ctcfinder.com/guide/cost/). ### 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](https://ctcfinder.com/guide/deadlines-2026-2027/). ## Nearby cities - [Fairfield](https://ctcfinder.com/testers/solano-county/fairfield/) — 11 listings, 10 mi - [Sonoma](https://ctcfinder.com/testers/sonoma-county/sonoma/) — 5 listings, 12 mi - [Vallejo](https://ctcfinder.com/testers/solano-county/vallejo/) — 8 listings, 13 mi - [Vacaville](https://ctcfinder.com/testers/solano-county/vacaville/) — 6 listings, 15 mi - [Winters](https://ctcfinder.com/testers/yolo-county/winters/) — 4 listings, 21 mi - [San Pablo](https://ctcfinder.com/testers/contra-costa-county/san-pablo/) — 7 listings, 23 mi - [Martinez](https://ctcfinder.com/testers/contra-costa-county/martinez/) — 7 listings, 23 mi - [Richmond](https://ctcfinder.com/testers/contra-costa-county/richmond/) — 3 listings, 25 mi - [Concord](https://ctcfinder.com/testers/contra-costa-county/concord/) — 7 listings, 26 mi - [Pittsburg](https://ctcfinder.com/testers/contra-costa-county/pittsburg/) — 5 listings, 27 mi