Monitored Circuits

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 do indicate an implied failure within a specified system, and that the problem must be diagnosed. If any monitor detects a problem affecting vehicle emissions, a Diagnostic Trouble Code (DTC) will be stored in PCM. The following monitors are used.

Catalyst Monitor
EVAP System Leak Detection Monitor
Fuel System Monitor
Misfire Monitor
Oxygen Sensor Heater Monitor
Oxygen Sensor 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 warm-up cycles for fuel system monitor and misfire monitor) if the recent malfunction does not reoccur in that time. For additional information on good trips and warm-up cycles, see TRIP INDICATORS .

NOTE: A warm-up cycle is defined as engine is started, an increase of 40°F in engine coolant temperature exists after engine is started and engine coolant temperature increases to at least 160°F.