Monitored Emission Control Systems

The OBD II system monitors all emission control systems that are on-board. Not all vehicles need every possible emission control system. For example, a vehicle may not be equipped with secondary air injection (AIR) or exhaust gas recirculation (EGR). The OBD II regulations require monitoring of the following; if equipped:

• Air conditioning system refrigerant
• Catalytic converter efficiency
• Comprehensive component monitoring-Emission related inputs and outputs
• Evaporative emissions (EVAP) system
• Fuel delivery system
• Heated catalyst monitoring
• Misfire monitoring
• Oxygen sensor system (O2S or HO2S)
• Oxygen sensor heater system (HO2S Heater)

For the specific DTCs required for each system, refer to Inspection/Maintenance (I/M) System DTC Table . Systems such as fuel delivery, misfire, and comprehensive components may not be listed in a system status list. These tests run continuously on some vehicles and may not require an indicator.