|I/M Program Information
OBD start date: January 2002
Exhaust I/M programs:
Most vehicles are ASM (5015/2525), visual (tamper), functional, and OBD inspected biennially. Registration denial program. Two-Speed Idle (TSI) used instead of ASM for vehicles that are not single-axle dyno compatible (i.e., vehicles with AWD or traction control issues), including trucks over 10,000 lb GVWR.
Vehicles less than 6 model-years old are exempt from biennial inspection.
Vehicles older than 1996 are inspected, but not for OBD, other than the visual MIL check.
All vehicles over 14,000 lb GVWR are currently exempt from the OBD-II Functional Check.
1998 and newer Diesel vehicles up to 14,000 GVWR are subject to Smog Check biennial inspection. The test includes a tamper check, a visible smoke test and an OBD check.
Heavy-Duty diesels are opacity inspected by the Air Resources Board.