Monitored Systems: Notes

There are new electronic circuit monitors that check fuel, emission, engine and ignition performance. These monitors use information from various sensor circuits to indicate overall operation of fuel, engine, ignition and emission systems and thus emissions performance of vehicle.

The fuel, engine, ignition and emission systems monitors do not indicate a specific component problem. They do indicate that there is an implied problem within one of systems and that a specific problem must be diagnosed.

If any of these monitors detect a problem affecting vehicle emissions, Malfunction Indicator (Check Engine) Lamp will be illuminated. These monitors generate Diagnostic Trouble Codes that can be displayed with check engine lamp or a scan tool.

The following is a list of system monitors:

• EGR Monitor (if equipped)
• Misfire Monitor
• Fuel System Monitor
• Oxygen Sensor Monitor
• Oxygen Sensor Heater Monitor
• Catalyst Monitor
• Evaporative System Leak Detection Monitor

The following is a description of each system monitor, and its DTC.