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 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.