Clean Truck Check (CTC): the California compliance guide

Who has to comply

The program covers nearly all non-gasoline heavy-duty vehicles with a gross vehicle weight rating above 14,000 lbs that operate in California — including out-of-state trucks, motorhomes, and agricultural vehicles, each with their own testing cadence. California-registered vehicles are also tied to DMV registration: unresolved CTC compliance can block registration renewal.

The three compliance obligations

• Annual compliance fee — paid per vehicle in CTC-VIS each year.
• Periodic emissions testing — most trucks test on a semi-annual cycle; motorhomes and agricultural vehicles test annually.
• Reporting — a passing test only counts once it is submitted to CTC-VIS by a credentialed tester before the compliance deadline.

Which test applies

Vehicles with an OBD-equipped engine (generally 2013 and newer engine model years) submit an OBD data test. Older engines and vehicles without usable OBD get an opacity test with a visual inspection (OVI) run to the SAE J1667 snap-idle procedure. See OBD vs opacity testing for the full breakdown.

How deadlines are set

California-plated vehicles are scheduled from the registration expiration month; out-of-state vehicles use the last digit of the VIN. Testing windows open 90 days before each deadline, which is why fleets that wait until the deadline month end up with downtime. Full schedule: Clean Truck Check deadlines and testing windows.

What happens if you miss a deadline

A missed deadline puts the vehicle out of compliance, exposes the operator to CARB enforcement and penalties, and can hold up DMV registration. A failed test must be repaired and retested before the vehicle is compliant again.

How shops stay ahead of it

Most repair shops manage this in spreadsheets until the fleet grows past a few dozen units. CTC Tracker replaces that: every vehicle carries its VIN, plate state, registration expiration, computed next CTC due date, test history with photos, and reminders at 90, 30, and 7 days — plus invoices generated straight from a logged test.