Circuit Description

PCM uses information from Crankshaft Position (CKP) sensor and Camshaft Position (CMP) sensor to determine when an engine misfire is occurring. By monitoring changes in crankshaft rotation for each cylinder, PCM counts individual misfire events. MIL illuminates when misfire rate equals or exceeds a predetermined count. A misfire rate that is high enough can cause catalytic converter to overheat under certain driving conditions. MIL will flash when conditions for catalytic converter overheating are present.

DTC will set when, ECT and IAT is greater than 19°F (-7°C), barometric pressure is greater than 75 kPa, engine speed is less than 4,000 RPM, fuel tank level is greater than 15 percent and TP sensor change is less than one degree/10 milliseconds. Conditions present for 5 seconds after engine start to one second from fuel shut-off.