Monitored Emission Control Systems

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The OBD-II System monitors all emission control systems that are on-board. Not all vehicles have a full complement of emission control systems. 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:

Air conditioning system.
Catalytic converter efficiency.
Comprehensive component monitoring. Emission related inputs and outputs.
Evaporative (EVAP) emissions system.
Exhaust Gas Recirculation (EGR) system.
Fuel delivery system.
Heated catalyst monitoring.
Misfire monitoring.
Oxygen sensor system (O2S or HO2S).
Oxygen sensor heater system (HO2S heater).
Secondary Air Injection (AIR) system.

For the specific DTCs required for each system, see INSPECTION/MAINTENANCE SYSTEM DTCS 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.