CARB Clean Truck Check for buses and coaches

Clean Truck Check is the Air Resources Board's heavy-duty inspection and maintenance program. It applies to diesel and other non-gasoline vehicles over 14,000 lbs GVWR that operate in California, and that description fits most motor coaches, party buses and full-size shuttle buses. Miss a deadline and the consequence is not a fine from CARB. It is a hold on your DMV registration, which then blocks the renewal, which then blocks the CPUC.

Three things you must do

1. Report the vehicle in CTC-VIS, CARB's online database, once. Every affected vehicle needs to be listed under your fleet.
2. Pay the annual compliance fee per vehicle — $32.13 for deadlines on or after January 1, 2026. It is paid in CTC-VIS by the vehicle's deadline.
3. Pass a periodic emissions test, submitted by a CARB-credentialed tester. Tests can be submitted up to 90 days before the deadline, which is the window to fix anything that fails.

How the deadlines fall

For a California-registered vehicle the compliance deadlines are tied to the DMV registration expiration date: one on that date and one six months later, repeating. So a coach whose registration expires each March 15 has Clean Truck Check deadlines on March 15 and September 15. Watchdog derives both from the registration date you give us and starts reminders 90 days out, when the test window opens.

What changes next

• October 2026: vehicles using the newer J1979-2 diagnostic protocol with deadlines from January 1, 2027 must be tested with a CARB-certified OBD device, not a generic reader.
• October 2027: testing moves from twice a year to four times a year for most fleets.

The registration-hold trap

The hold is placed under SB 210 when a deadline passes without compliance, and it stays until compliance is confirmed. If it lands in the weeks before your registration expires, you cannot renew, the plate lapses, and the CPUC will not process equipment changes or a reinstatement on a vehicle with an expired registration. Everything after that is a cascade you start from the emissions test.