DIAGNOSTICS
MIL — function Indicator Lamp
Definition
The amber engine-shaped warning lamp on the instrument cluster that illuminates when the ECU stores an emission-related DTC. Required by OBD-II legislation since 1996.
Why workshops care
MIL state is reported via OBD Mode 01 PID 01. A MIL with a stored DTC is what every emissions / MOT inspector looks for first. Suppressing a code without fixing the cause leaves the vehicle technically non-compliant.