Frequently asked questions

Clean Truck Check is the California Air Resources Board (CARB) inspection and maintenance program for heavy-duty vehicles. It requires periodic emissions testing of covered diesel and alternative-fuel trucks so that emissions-control systems are kept working and repaired.

Most diesel and alternative-fuel vehicles over 14,000 lb GVWR that operate in California are covered, including out-of-state and Mexico-registered trucks that drive in the state. Some exemptions exist. Check your vehicle in CARB’s CTC-VIS system or ask us and we will help you work it out.

Most covered trucks currently test twice a year. Under the original rule, OBD-equipped vehicles move to four tests a year starting October 1, 2027, and a bill has proposed reducing testing to once a year. Requirements can change, so always confirm your deadlines in CARB’s CTC-VIS system.

No. Diesel Dynamix is an independent testing service. CARB runs the Clean Truck Check program; we provide mobile testing so you can meet its requirements. For official rules and deadlines, see CARB’s Clean Truck Check website.

Yes. Trucks over 14,000 lb GVWR that are registered in other states or in Mexico are covered when they operate in California. They must be reported in CTC-VIS and keep their testing up to date. We test out-of-state trucks anywhere in Southern California.

There are two parts: CARB’s annual compliance fee per vehicle, paid in CTC-VIS, and the tester’s fee for each test. Our price depends on the number of trucks, the test type and the location, with per-truck pricing for fleets. Call or WhatsApp (858) 342-8328 for a quote.

The truck becomes non-compliant. California-registered vehicles can face a DMV registration hold, and non-compliant trucks can be cited and penalized by CARB. Get tested as soon as possible: we can often schedule a mobile test quickly.

Yes. Diesel Dynamix is a mobile testing service. We come to your yard, jobsite, terminal or parking location anywhere in Southern California, so you never drive to a test center.

An OBD test is typically quick once we are connected to the truck. Smoke opacity tests take longer because the engine must be warmed up. For fleets, we plan the visit so trucks rotate through without holding up dispatch.

The truck’s VIN, access to the vehicle and keys, and a safe level place to park. For smoke opacity testing the engine should be able to reach normal operating temperature. We will confirm everything when we schedule.

We explain the result and what it means in plain English. Your truck will need repairs to its emissions-control system before it can pass a retest. We can schedule the retest once repairs are done.

Warm the engine to full operating temperature, fix exhaust leaks and engine faults, keep air filters and injectors in good shape, and make sure any diesel particulate filter is present and working. Well-maintained trucks usually pass.

Yes. Tell us how many trucks you run and where they are parked. We schedule fleet visits to test as many trucks as possible per trip and can set up recurring testing so you never miss a deadline.