Circuit Description

PCM uses Crankshaft Position (CKP) sensor and Camshaft Position (CMP) sensor to monitor changes in crankshaft rotation for each cylinder to detect a misfire. When misfire rate equals or exceeds a count indicating engine condition has deteriorated, MIL will illuminate. If misfire rate is significant, MIL will flash, indicating a catalytic converter damaging condition. DTC P0300 will set when engine speed is 200-1000 RPM, battery voltage is 9-17 volts, and engine coolant temperature is 20-254°F (-7-123°C).

When DTC sets, MIL will illuminate after 2 consecutive ignition cycles in which diagnostic runs with active fault causing deterioration in emissions. MIL will flash if misfire is severe enough to cause catalyst damage.