---
title: "Holly Smog — Clean Truck Check, San Carlos, CA | CTC Finder"
description: "Holly Smog in San Carlos, CA is on CARB's Clean Truck Check tester list with 2 credentialed testers. Offers mobile testing, OBD testing, motorhome testing…"
url: "https://ctcfinder.com/tester/holly-smog-san-carlos/"
updated: "2026-11-01"
publisher: "CTC Finder (independent directory, not affiliated with CARB)"
---

# Holly Smog

Clean Truck Check tester in San Carlos, 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 | 501 Old County Rd Suite A, San Carlos, CA 94070 |
| County | San Mateo County |
| Phone | (650) 595-1388 |
| Mobile testing | Yes |
| OBD testing | Yes |
| Smoke opacity (non-OBD) | No |
| Motorhomes | Yes |
| Credentialed testers | 2 |
| Last verified | 2026-11-01 |

## Which trucks Holly Smog 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 | 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 Carbcheck1 in San Carlos, about 1 mile away. [See listing](https://ctcfinder.com/tester/carbcheck1-san-carlos/).

## Clean Truck Check testers in San Mateo County

Holly Smog 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.

## 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 Holly Smog offer mobile Clean Truck Check testing?

Yes. Holly Smog 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 Holly Smog test a 2012 or older diesel truck?

Holly Smog does not list smoke opacity testing, which older non-OBD diesel trucks need. The nearest listed tester that does is [Carbcheck1](https://ctcfinder.com/tester/carbcheck1-san-carlos/) (about 1 mile). Trucks from 2013 on get an OBD scan instead.

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

Holly Smog has not published prices with us; call (650) 595-1388 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 Holly Smog a CARB-credentialed tester?

Holly Smog appears on CARB's public Clean Truck Check tester list with 2 credentialed testers, 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

- **[Carbcheck1](https://ctcfinder.com/tester/carbcheck1-san-carlos/)** — San Carlos, CA 94070 — (650) 430-3981 — 1 mi. Services: mobile testing, OBD testing, smoke opacity (non-OBD) testing, motorhome testing.
- **[Balboni Electric](https://ctcfinder.com/tester/balboni-electric-redwood-city/)** — 823 Cleveland St, Redwood City, CA 94061 — (650) 766-4997 — 3 mi. Services: mobile testing, OBD testing, smoke opacity (non-OBD) testing, motorhome testing.
- **[Filthy Busters Inc.](https://ctcfinder.com/tester/filthy-busters-inc-redwood-city/)** — 1249 Sabrina Ct, Redwood City, CA 94061 — (510) 326-5901 — 3 mi. Services: mobile testing, OBD testing, smoke opacity (non-OBD) testing, motorhome testing.
- **[Less Smog Check](https://ctcfinder.com/tester/less-smog-check-san-mateo/)** — 3925 S El Camino Real, San Mateo, CA 94403 — (669) 377-4881 — 3 mi. Services: mobile testing, OBD testing, smoke opacity (non-OBD) testing, motorhome testing.
- **[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 — 3 mi. Services: mobile testing, OBD testing, motorhome testing.
- **[Peninsula Truck Repair, INC.](https://ctcfinder.com/tester/peninsula-truck-repair-inc-redwood-city/)** — 3018 Spring St, Redwood City, CA 94063 — (831) 419-7042 — 4 mi. Services: mobile testing, OBD testing, smoke opacity (non-OBD) testing, motorhome testing.