Circuit/System Description

The engine control module (ECM) uses information from the crankshaft position (CKP) sensor in order to determine when an engine misfire is occurring. Information from the camshaft position (CMP) sensor is used by the ECM to determine which cylinder is misfiring. By monitoring variations in the crankshaft rotation speed for each cylinder, the ECM is able to detect individual misfire events. Under certain driving conditions, a misfire rate that is high enough can cause the 3-way catalytic converter (TWC) to overheat, possibly damaging the converter. The malfunction indicator lamp (MIL) will flash ON and OFF when the conditions for TWC overheating are present, and DTC P0300 is set.