Heavy-Duty Diesel Inspection & Periodic Smoke Inspection Programs
The Periodic Smoke Inspection Program (PSIP) and the Heavy-Duty Inspection and Maintenance Program (HD I/M) are inspection and smog check programs to ensure polluting, poorly maintained heavy-duty vehicles operating in California are quickly identified and repaired.
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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.
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