---
title: "Karl Grothman — Clean Truck Check, Concord, CA | CTC Finder"
description: "Karl Grothman in Concord, 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/karl-grothman-concord/"
updated: "2026-11-01"
publisher: "CTC Finder (independent directory, not affiliated with CARB)"
---

# Karl Grothman

Clean Truck Check tester in Concord, CA (Contra Costa 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 | Concord, CA 94521 |
| County | Contra Costa County |
| Phone | (925) 435-9674 |
| Mobile testing | Yes |
| OBD testing | Yes |
| Smoke opacity (non-OBD) | Yes |
| Motorhomes | Yes |
| Credentialed testers | 1 |
| Last verified | 2026-11-01 |

## Which trucks Karl Grothman 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 Contra Costa County

Karl Grothman 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 Concord itself there are 7 listed businesses, 6 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 Karl Grothman offer mobile Clean Truck Check testing?

Yes. Karl Grothman 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 Karl Grothman test a 2012 or older diesel truck?

Yes. Karl Grothman 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 Karl Grothman charge for a Clean Truck Check?

Karl Grothman has not published prices with us; call (925) 435-9674 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 Karl Grothman a CARB-credentialed tester?

Karl Grothman 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

- **[Bayside Mobile Mechanic Service](https://ctcfinder.com/tester/bayside-mobile-mechanic-service-concord/)** — 3160 Cowell Rd, Concord, CA 94518 — (925) 766-4292 — 3 mi. Services: mobile testing, OBD testing, smoke opacity (non-OBD) testing.
- **[NQR Mobile Service - SF Bay Area & Nor Cal](https://ctcfinder.com/tester/nqr-mobile-service-sf-bay-area-and-nor-cal-concord/)** — 2750 Cloverdale Ave SF BAY AREA & NORCAL, Concord, CA 94518 — (925) 276-2215 — 3 mi. Services: mobile testing, OBD testing.
- **[Amunique](https://ctcfinder.com/tester/amunique-bay-point/)** — 3628 Willow Pass Rd, Bay Point, CA 94565 — (925) 915-7888 — 4 mi. Services: mobile testing, OBD testing.
- **[Brothers](https://ctcfinder.com/tester/brothers-pittsburg/)** — 3 Shadelands Ct, Pittsburg, CA 94565 — (626) 814-5541 — 4 mi. Services: mobile testing, OBD testing, smoke opacity (non-OBD) testing, motorhome testing.
- **[Cristian Preza](https://ctcfinder.com/tester/cristian-preza-pittsburg/)** — Pittsburg, CA 94565 — (925) 446-9660 — 4 mi. Services: not listed.
- **[Jasbir Truck Repair](https://ctcfinder.com/tester/jasbir-truck-repair-pittsburg/)** — 1646 Birdhaven Way, Pittsburg, CA 94565 — (925) 864-2335 — 4 mi. Services: mobile testing, OBD testing.