California Air Resources Board

This webpage helps owners of vehicles respond to a Notice to Submit to Testing letter issued by CARB Enforcement under HD I/M. 

To help you get your vehicle tested, here is a link to a list of commercial CARB-credentialed Clean Truck Check (HD I/M) Testers with contact information: 

• Credentialed Clean Truck Check (HD I/M) Tester and PSIP Smoke Tester Public Lists

Alternatively, Clean Truck Check (HD I/M) allows a vehicle owner or a fleet mechanic to conduct the testing and reporting that is required. A tester needs to take the Clean Truck Check (HD I/M) training, pass the exam, and use the correct test equipment, as follows:

• Free on-line Clean Truck Check (HD I/M) Tester Training Course and Exam

Test Equipment for engine model year 2013 and newer:

• CARB-Approved On-Board Diagnostics (OBD) Test Devices

Test Equipment for engine model year 2012 and older:

• CARB-Approved Smoke Opacity Meters

If you are submitting a smoke opacity test for your 2012 or older model year engine, you must also submit a completed Clean Truck Check (HD I/M) Vehicle Emissions Control Equipment Inspection Form:

• Vehicle Emissions Control Equipment Inspection Form

If your vehicle needs repair to demonstrate Clean Truck Check (HD I/M) compliance, you must submit a completed Demonstration of Compliance form (click link below) and send copies of repair receipts.

• Demonstration of Compliance Form

Return to Clean Truck Check (HD I/M) & Periodic Smoke Inspection Programs