---
title: "What Is Clean Truck Check? California's Truck Emissions Test Explained"
description: "Clean Truck Check is California's emissions testing program for diesel and alternative-fuel trucks over 14,000 lbs GVWR. Who must test, which test you need and…"
url: "https://ctcfinder.com/guide/what-is-clean-truck-check/"
updated: "2026-10-30"
publisher: "CTC Finder (independent directory, not affiliated with CARB)"
---

# What is Clean Truck Check?

Updated 2026-10-30. Source: CTC Finder (https://ctcfinder.com/guide/what-is-clean-truck-check/). Independent; not affiliated with CARB.

**Short answer:** Clean Truck Check (CTC) is the California Air Resources Board's (CARB) heavy-duty inspection and maintenance program, also called HD I/M. Nearly every diesel and alternative-fuel vehicle with a GVWR over 14,000 lbs that drives on California roads must be reported in CARB's CTC-VIS system, pay an annual compliance fee and pass periodic emissions tests done by a **CARB-credentialed tester**. Most trucks test twice a year today; trucks with onboard diagnostics (OBD) move to four tests a year beginning October 2027.

## Who has to comply

CARB says the program covers "nearly all diesel and alternative fuel heavy-duty vehicles" over 14,000 lbs GVWR. That includes:

- commercial trucks, buses and tractors, including hybrids;
- government, transit and school vehicles;
- personal vehicles in that weight class;
- **out-of-state and out-of-country vehicles** when they operate in California (see [out-of-state trucks](https://ctcfinder.com/guide/out-of-state-trucks/));
- California-registered motorhomes (tested once a year).

Gasoline vehicles are not covered.

### Exempt vehicles

CARB's overview fact sheet lists these exemptions: zero-emission vehicles, military tactical vehicles, emergency vehicles, historical vehicles, new engines certified to the optional 0.01 g/bhp-hr NOx standard (2023–2027 only), motorhomes registered outside California and vehicles under an experimental permit.

## The four things every truck needs

To be compliant, CARB requires that a vehicle:

1. is **reported in CTC-VIS**, CARB's online Clean Truck Check Vehicle Inspection System ([how to register](https://ctcfinder.com/guide/how-to-register-ctc-vis/));
2. has its **annual compliance fee** paid ($32.13 per vehicle in 2026, $33.12 in 2027);
3. has a **passing emissions test** submitted by a credentialed tester before each deadline;
4. has **no outstanding enforcement violations**.

## Which test does my truck need?

| Vehicle | Test |
|---|---|
| Diesel, model year 2013 and newer | OBD scan with a CARB-certified device |
| Alternative fuel, model year 2018 and newer | OBD scan |
| Diesel, model year 2012 and older (non-OBD) | Smoke opacity test (SAE J1667) plus visual inspection |
| Alternative fuel, model year 2017 and older | Visual inspection only |

An OBD test takes a few minutes: the tester connects a certified device to the diagnostic port and the result goes to CARB. Smoke opacity testing needs a smoke meter, so fewer testers offer it. On CTC Finder you can filter for testers that do smoke opacity tests.

## Who can test my truck

Only a **CARB-credentialed tester** can submit a Clean Truck Check test. Credentials come from CARB's free online course and exam and are valid for two years. You can test your own trucks only if you are credentialed yourself. Many testers are mobile and come to your yard.

CARB keeps a public list of testers who choose to be listed, but listing is optional and the list is hard to search by location. CTC Finder organizes that list by county, city and ZIP code: 2,867 testing businesses in California, 2,543 of them mobile. [Find a tester near you](https://ctcfinder.com/testers/).

## How deadlines work

For California-registered vehicles, deadlines follow the DMV registration expiration date and every six months after it. Vehicles registered elsewhere follow a schedule based on the last digit of the VIN. You can test up to 90 days before a deadline. Details: [deadlines 2026–2027](https://ctcfinder.com/guide/deadlines-2026-2027/).

## What happens if you don't comply

Non-compliance can lead to a DMV registration hold, notices of violation and civil penalties; CARB's FAQ cites potential penalties of $1,000 to $10,000 per day per vehicle under state law. CARB also screens trucks on the road with remote emissions monitoring devices (REMD). See [fines and penalties](https://ctcfinder.com/guide/fines-and-penalties/).

## Frequently asked questions

### Is Clean Truck Check the same as a smog check?

No. Smog Check (run by the Bureau of Automotive Repair) covers cars and light trucks. Clean Truck Check is CARB's program for heavy-duty diesel and alternative-fuel vehicles over 14,000 lbs GVWR. Some smog stations are also credentialed CTC testers.

### Do pickup trucks need Clean Truck Check?

Only if the manufacturer's GVWR is over 14,000 lbs and the vehicle is diesel or alternative fuel. Most full-size pickups are under that rating.

### Does my motorhome need Clean Truck Check?

California-registered motorhomes over 14,000 lbs GVWR test once a year. Motorhomes registered outside California are exempt. Motorhomes used commercially follow the twice-a-year schedule.

### What is CTC-VIS?

CTC-VIS is CARB's online system where owners report vehicles, pay the annual fee, see deadlines and download compliance certificates. Testers also use it to submit results.

## Sources

- CARB, [Clean Truck Check program page](https://ww2.arb.ca.gov/our-work/programs/CTC)
- CARB, [Clean Truck Check overview fact sheet](https://ww2.arb.ca.gov/clean-truck-check-overview-fact-sheet)
- CARB, [Clean Truck Check FAQ](https://ww2.arb.ca.gov/resources/fact-sheets/clean-truck-check-faq-0)
- CARB, [Requirements for vehicles subject to semi-annual compliance](https://ww2.arb.ca.gov/clean-truck-check-requirements-vehicles-subject-semi-annual-compliance)