Test deadline
How Often Is Clean Truck Check Due
How often is Clean Truck Check due? Most California heavy-duty vehicles test twice a year. Agricultural vehicles and motorhomes often test annually. OBD-equipped trucks typically move to quarterly testing in October 2027. Enter your last passing test for the next window. This unofficial calculator is independent — not CARB.gov — and does not issue the official certificate.
Last updated . Educational estimate only. We do not set CARB’s official testing period. Confirm cadence on CARB’s Clean Truck Check overview. CARB Test Finder does not issue the official certificate.
How to check
How to check your Clean Truck Check deadline
Enter the last passing test, vehicle category, OBD status, and California use. Then read the unofficial next window.
Enter the last pass
Use the date on the passing report, or choose never tested if this vehicle has not completed Clean Truck Check yet.
Choose the category
Heavy-duty trucks and buses usually test semi-annually. Agricultural vehicles and motorhomes often test annually.
Say if it is OBD-equipped
OBD engines are typically 2013 and newer. Quarterly testing starts October 2027.
Confirm California use
Trucks that never operate in California are typically outside the program until they enter the state.
Read the next window
See the cadence, next due date, and days remaining. Book a tester if you are overdue or due soon.
Schedule
Clean Truck Check testing schedule
Most covered trucks test every six months. Agricultural vehicles and motorhomes often test yearly. OBD-equipped units typically move to quarterly testing in October 2027.
| Vehicle | How often | When this applies |
|---|---|---|
| Most heavy-duty trucks and buses | Every 6 months (semi-annually) | Current rule |
| Agricultural vehicles and motorhomes | Every 12 months (annually) | Current rule |
| OBD-equipped (typically 2013+) | Every 3 months (quarterly) | From October 2027 |
Source: Clean Truck Check overview. This table is unofficial — not CARB.gov.
FAQ
Clean Truck Check due date FAQs
How often testing is due, the next window after a passing test, and the October 2027 OBD change. This calculator is unofficial — not CARB.gov.
Most covered heavy-duty vehicles test semi-annually. Agricultural vehicles and motorhomes often test annually. OBD-equipped vehicles typically move to quarterly testing in October 2027.