California’s Clean Truck Check now hits almost every diesel truck over 14,000 lb that runs in the state — including out-of-state fleets. Miss it and your registration gets blocked. Enter a truck and X3 tells you what test you owe, when it’s due, and your risk.
Free · instant · X3 analysis of CARB rules — verify at CARB

The money isn’t in running the test — it’s in not losing your registration, eating a fine, or getting turned around at the California line. Most owners have no idea what applies to their trucks until a notice shows up.
If your truck operates in California — even once — Clean Truck Check can apply. Fleets based in Texas, Ohio, Georgia get caught off guard because they assume it’s a “California problem.” It’s a your-truck-in-California problem.
2013-and-newer diesel (2018+ alt-fuel) get an OBD scan; 2012-and-older diesel get a smoke-opacity test plus a visual. Twice a year now, four times a year from October 2027. Miss a window and the registration block follows.
The Advanced Clean Trucks / Advanced Clean Fleets purchase mandates were revoked in 2025, so nobody’s forcing you to buy an electric truck. But Clean Truck Check — the testing program with the registration teeth — is very much alive. We track what’s real, not the headlines.
A blocked registration parks the truck. We make sure that never happens.

X3 figures out what each truck owes, when it’s due, and what it’ll cost — then keeps watch so nothing lapses.
VIN or just fuel, engine year, GVWR and where you run. X3 determines Clean Truck Check applicability for each unit — in-state and out-of-state.
Which test (OBD vs opacity), how often, the annual fee, and each truck’s status: compliant, due soon, or registration-block risk. Plus a fleet compliance score.
Deadline alerts before anything lapses, and an AI assistant for “can my 2012 truck run in California?” — answered against the current rules, with the CARB source.
Self-serve, AI-run. CARB fees and the test itself are paid separately. Pricing illustrative.
One or two trucks, never lapsed.
Whole fleet, one dashboard. +$3/truck over 25.
Before you buy a used truck.