On-Board Diagnosis Logic

ON-BOARD DIAGNOSIS LOGIC
If the absence of Exhaust Gas Recirculation (EGR) flow is detected by EGR temperature sensor under the condition that calls for EGR, a low flow malfunction is diagnosed.

If EGR temperature sensor detects EGR flow under the condition that does not call for EGR, a high-flow malfunction is diagnosed.

OVERALL FUNCTION CHECK
Use this procedure to check the overall EGR function. During this check, a DTC might not be confirmed.

Before starting with the following procedure, check the engine coolant temperature of the freeze frame data with CONSULT or Generic Scan Tool.

If the engine coolant temperature is higher than or equal to 70°C (158°F), perform only "Procedure for malfunction A".
If the engine coolant temperature is lower than 65°C (149°F), perform both "Procedure for malfunction A" and "Procedure for malfunction B".

If the freeze frame data for another malfunction is stored in the Engine Control Module (ECM), perform both "Procedure for malfunction A" and "Procedure for malfunction B". In this case, check DTCs in the ECM and perform inspections one by one based on "INSPECTION PRIORITY".