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:

The air conditioning system
The catalytic converter efficiency
Comprehensive component monitoring-Emission related inputs and outputs
The evaporative emissions (EVAP) system
The EGR System
The fuel delivery system
Heated catalyst monitoring
Misfire monitoring
The oxygen sensor system (O2S or HO2S)
The oxygen sensor heater system (HO2S heater)
The AIR system

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 and do not require an I/M System Status indicator.

Inspection/Maintenance (I/M) System Check

Step	Action	Value(s)	Yes	No
1	Perform the Diagnostic System Check - Vehicle . IMPORTANT: Many DTC related repairs will instruct the technician to clear the DTC information. This procedure will reset ALL of the I/M System Status indicators to NO, and require performing the I/M Complete System Set Procedure. Repair any DTCs or driveability concerns that would prevent the I/M System Status tests from completing. Did you find and repair a DTC or driveability concern?	-	Go to Step 3	Go to Step 2
2	Review any service bulletins for software updates that may prevent inspection/maintenance (I/M) readiness. Perform any reprogramming or repairs indicated by the service bulletins. Was a reprogramming or repair service required?	-	Go to Inspection/Maintenance (I/M) Complete System Set Procedure	Go to Step 3
3	Observe the I/M System Status display with a scan tool. Is more than one test indicating a NO status?	-	Go to Inspection/Maintenance (I/M) Complete System Set Procedure	Go to the I/M System Set Procedure for the indicated systems that have not updated