Exhaust Gas Recirculation (EGR) Cooler System Monitor

EXHAUST GAS RECIRCULATION (EGR) COOLER SYSTEM MONITOR

The EGR cooler system, including the EGR cooler bypass valve, is monitored by comparing a modeled EGR gas temperature downstream of the EGR cooler to an actual temperature sensor value. Both under cooling and over cooling conditions are monitored. The over cooling monitor occurs when the engine is in normal closed loop operation, the engine coolant temperature is between 60-90°C (140-194°F), and no air system DTCs are present. The under cooling monitor occurs when the engine is in normal closed loop operation, the engine coolant temperature is above 70°C (158°F), and no air system DTCs are present. If the difference between the modeled EGR gas temperature downstream of the EGR cooler and the actual EGR gas temperature sensor value is greater than a calibrated amount a concern is detected.

The monitor detects an under cooling condition if the EGR cooler is inoperative or EGR cooler bypass valve is stuck open. The monitor detects an over cooling condition if the EGR cooler bypass valve is stuck closed.