Extinguishing the MIL

Once the mil is turned on by an emissions diagnostic, that diagnostic must run and pass for three consecutive driving cycles in order for the MIL to go out automatically.

Misfire and fuel trim faults have unique requirements. If the DTCs were set by either a misfire or fuel trim problem the MIL will stay on until the fault does not reappear during 3 consecutive driving cycles under similar operating conditions (coolant temperature, engine rpm and load).

Clearing the fault codes with Intellegant Saab Tester (ISAT) or by disconnecting the battery will also turn off the MIL. Pulling a battery cable as a quick & dirty means of turning off the MIL and clearing codes should be avoided as it will also crash the memories in other systems, affecting quite a few calibration and adaption functions.