Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
Exhaust Gas Recirculation (EGR) Cooler System Monitor - All Others
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.
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.