---
title: "Less Smog Check — Clean Truck Check, San Mateo, CA"
description: "Less Smog Check in San Mateo, CA is on CARB's Clean Truck Check tester list. Offers mobile testing, OBD testing, smoke opacity (non-OBD) testing, motorhome…"
url: "https://ctcfinder.com/tester/less-smog-check-san-mateo/"
updated: "2026-11-01"
publisher: "CTC Finder (independent directory, not affiliated with CARB)"
---

# Less Smog Check

Clean Truck Check tester in San Mateo, CA (San Mateo County).

> 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.

| Field | Value |
|---|---|
| Location | 3925 S El Camino Real, San Mateo, CA 94403 |
| County | San Mateo County |
| Phone | (669) 377-4881 |
| Mobile testing | Yes |
| OBD testing | Yes |
| Smoke opacity (non-OBD) | Yes |
| Motorhomes | Yes |
| Credentialed testers | 1 |
| Last verified | 2026-11-01 |

## Which trucks Less Smog Check can test

| 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 | Yes |
| California-registered motorhome | Same test as above by engine year, once a year | Yes |

## Clean Truck Check testers in San Mateo County

Less Smog Check is one of 31 testing businesses in San Mateo County on CARB's public tester list. 27 of them offer mobile testing and 17 do smoke opacity tests. In San Mateo itself there are 4 listed businesses, 3 of them mobile.

## 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](https://ctcfinder.com/guide/deadlines-2026-2027/). You can test up to 90 days before a deadline. Free email reminders: https://ctcfinder.com/reminders/

## Frequently asked questions

### Does Less Smog Check offer mobile Clean Truck Check testing?

Yes. Less Smog Check says on CARB's tester list that it offers mobile testing, so it can come to your yard or job site. Ask about a trip fee when you call.

### Can Less Smog Check test a 2012 or older diesel truck?

Yes. Less Smog Check lists smoke opacity testing, the test CARB requires for diesel trucks of model year 2012 and older (no OBD). See [OBD vs smoke opacity](https://ctcfinder.com/guide/obd-vs-smoke-opacity-test/).

### How much does Less Smog Check charge for a Clean Truck Check?

Less Smog Check has not published prices with us; call (669) 377-4881 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](https://ctcfinder.com/guide/cost/).

### Is Less Smog Check a CARB-credentialed tester?

Less Smog Check 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 nearby

- **[Mobile Golden State Emissions San Mateo](https://ctcfinder.com/tester/mobile-golden-state-emissions-san-mateo-san-mateo/)** — 3500 Edison St., San Mateo, CA 94403 — (925) 818-1831 — 1 mi. Services: mobile testing, OBD testing, motorhome testing.
- **[Charlotte Cuschieri](https://ctcfinder.com/tester/charlotte-cuschieri-san-mateo/)** — San Mateo, CA 94402 — (650) 455-8824 — 1 mi. Services: OBD testing, motorhome testing.
- **[EV Auto Service LLC](https://ctcfinder.com/tester/ev-auto-service-llc-san-mateo/)** — 110 S Claremont St, San Mateo, CA 94401 — (650) 293-7738 — 3 mi. Services: mobile testing, OBD testing, motorhome testing.
- **[Carbcheck1](https://ctcfinder.com/tester/carbcheck1-san-carlos/)** — San Carlos, CA 94070 — (650) 430-3981 — 3 mi. Services: mobile testing, OBD testing, smoke opacity (non-OBD) testing, motorhome testing.
- **[Holly Smog](https://ctcfinder.com/tester/holly-smog-san-carlos/)** — 501 Old County Rd Suite A, San Carlos, CA 94070 — (650) 595-1388 — 3 mi. Services: mobile testing, OBD testing, motorhome testing.
- **[Mohammad Najafpir](https://ctcfinder.com/tester/mohammad-najafpir-burlingame/)** — Burlingame, CA 94010 — (650) 771-8865 — 4 mi. Services: mobile testing, OBD testing, motorhome testing.