Monitored Emission Control Systems

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 AIR or 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 Emissions (EVAP) system.
• Exhaust Gas Recirculation (EGR) system.
• Fuel delivery system.
• Heated catalyst monitoring.
• Misfire monitoring.
• Oxygen Sensor (O2S or HO2S) system.
• Oxygen Sensor Heater (HO2S Heater) system.
• Secondary Air Injection (AIR) system.

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