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 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.

• Catalyst Monitor
• Engine Misfire Monitor
• Evaporative Emissions System Leak And Purge Detection Pump Monitor
• Exhaust Gas Recirculation System Monitor
• Fuel System Monitor
• Oxygen Sensor Monitor
• Oxygen Sensor Heater 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 if the recent malfunction does not reoccur in that time. For additional information on good trips and warm-up cycles, see TRIP INDICATOR  .