Clean Truck Check (HD I/M) Frequently Asked Questions
Confused about CARB regulations? You aren’t alone. The Clean Truck Check (Heavy-Duty Inspection and Maintenance) program is a major shift from the old rules. Here is what you need to know to keep your truck legal and on the road.
What year trucks need the Clean Truck Check?
Virtually all heavy-duty diesel and alternative fuel vehicles with a Gross Vehicle Weight Rating (GVWR) over 14,000 lbs operating in California are subject to the program. This includes out-of-state trucks.
However, the type of test depends on your model year:
- 2013 and Newer Diesel Engines: Required to undergo an OBD (On-Board Diagnostics) test. This is the service we specialize in at Louie’s Truck Check.
- 2012 and Older Diesel Engines: Required to pass a smoke opacity test and visual inspection.
- Alternative Fuel Vehicles: 2018 and newer engines require OBD testing.
How often do I need to test my 2013+ Diesel?
Starting in 2025, most trucks require testing twice a year (every 6 months).
- Deadlines: Your testing deadlines are shown in CTC-VIS (Testing Details).
- How they’re set: Many vehicles follow DMV renewal date; some DMV-exempt vehicles follow a VIN-based schedule.
- Future Change: Effective October 1, 2027, OBD-equipped vehicles must submit tests four times per year (quarterly).
Note: Agricultural vehicles and California-registered motorhomes generally only require testing once per year.
How to Pass the Clean Truck Check: 3 Tips from the Pro
As a Clean Truck Check tester, we see trucks fail for simple reasons that could have been avoided. Here is how to make sure your 2013+ diesel is ready for its OBD test:
1. Do NOT Clear Your Codes Right Before Testing Many drivers think clearing a “Check Engine” light immediately before an inspection will help them pass. It will not. The Clean Truck Check system checks for “Permanent Diagnostic Trouble Codes (PDTCs).” If you clear codes, the computer resets its “readiness monitors,” and your truck will be rejected until you drive it enough to reset them. If you have a repair made, drive the vehicle for a few days before bringing it in.
2. Check Your Engine Light If your Check Engine Light (MIL) is currently on, you will automatically fail the OBD test. You must have the underlying mechanical issue fixed before you pay for a test.
3. Bring Your Documents To make your appointment fast and smooth, please have your DMV Registration card ready. We need to verify your VIN and license plate exactly as they appear in the DMV system to ensure your certificate is processed correctly with CARB.
Ready to schedule? Call/Text: 909-475-7664 or visit our Contact / Appointments page to send us a message.
Scheduling available in English and Spanish — Se habla Español