If You Received a Notice to Submit to Testing (NST) Letter
This site 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 HD I/M Testers with contact information:
Alternatively, 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 HD I/M training, pass the exam, and use the correct test equipment, as follows:
Test Equipment for engine model year 2013 and newer:
Test Equipment for engine model year 2012 and older:
If you are submitting a smoke opacity test for your 2012 or older model year engine, you must also submit a completed HD I/M Vehicle Emissions Control Equipment Inspection Form:
If your vehicle needs repair to demonstrate HD I/M compliance, you must submit a completed Demonstration of Compliance form (click link below) and send copies of repair receipts.
If you are having difficulties finding a HD I/M Tester or procuring testing equipment, please contact CARB Enforcement
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