Monitored Emission Control Systems

OBD-II system monitors all emission control systems. OBD-II regulations require monitoring of the following:

• Air conditioning system.
• Catalytic converter efficiency.
• Evaporative Emissions (EVAP) 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 specific DTCs required for each system, see INSPECTION/MAINTENANCE SYSTEM DIAGNOSTIC TROUBLE CODES  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.