The malfunction indicator lamp (MIL) lights in the event of misfiring

WARNING: This page is about a different car, the 2002 Volvo C70, 2001 Volvo C70, 2000 Volvo C70, 1999 Volvo C70, and 1998 Volvo C70. However, it is still accessible from the selected car via links, so may be relevant.

The malfunction indicator lamp (MIL) lights in the event of misfiring. If there is risk of damage to the three way catalytic converter due to misfiring, the malfunction indicator lamp (MIL) will flash and then switch to a constant light.

The engine control module (ECM) registers and stores the RPM and load parameters within which the misfire occurred. For the diagnostic trouble code (DTC) to be stored, the misfire must occur a further two times within the same RPM and load parameters. The malfunction indicator lamp (MIL) is lit if the diagnostic trouble code (DTC) for misfire is stored in the previous operating cycle and a new diagnostic trouble code (DTC) for misfire is stored in the next operating cycle.

If the misfire stops, the requirements for the RPM and load parameters must be met without misfiring before the engine control module (ECM) will begin counting down to extinguish the warning lamp and erase stored diagnostic trouble codes (DTCs).