Monitored Circuits

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The PCM contains electronic circuit monitors that monitor fuel, vehicle emissions, engine and ignition system performance. Monitors use information from various sensor circuits for system monitoring. Monitors do not indicate a specific component failure, but indicate an implied failure within a specified system, and that problem must be diagnosed. If any monitor detects a problem affecting vehicle emissions, a Diagnostic Trouble Code (DTC) will be stored in PCM memory. The following monitors are used.

Engine Misfire Monitor
Fuel System Monitor
Oxygen Sensor Monitor
Oxygen Sensor Heater Monitor
Catalyst Monitor
EVAP System Leak Detection Pump Monitor
EGR Monitor

After 3 good trips, PCM will turn off the MIL. At that time, the PCM will automatically switch the trip counter to a warm-up cycle counter. The PCM will erase DTCs after 40 warm-up cycles (80 for fuel system monitor or misfire monitor) if the recent malfunction does not reoccur in that time. For additional information on good trips and warm-up cycles, see Trip Indicator .