Exhaust Gas Temperature (EGT) Sensor
A sensor that measures the temperature of exhaust gases to protect engine components, especially turbochargers and emissions systems.
An Exhaust Gas Temperature (EGT) sensor is a probe mounted in the exhaust manifold or exhaust pipe that measures the temperature of the exhaust gases. The engine control unit (ECU) monitors EGT data to protect critical components like the turbocharger, catalytic converter, and diesel particulate filter (DPF) from overheating. It also helps control fuel injection timing and emission reduction systems.
In diesel engines, EGT sensors are critical for monitoring DPF regeneration, where exhaust temperatures must be raised to burn off accumulated soot. If exhaust temperatures climb too high, it can melt the internal components of a turbocharger or crack the exhaust manifold. If an EGT sensor fails, the ECU will typically enter a safe mode (limp mode) and restrict engine power to prevent potential engine damage.
Symptoms of a failing EGT sensor include decreased fuel efficiency, poor engine acceleration, a Check Engine Light, and the vehicle failing emissions tests. Diagnostics involve reading OBD-II trouble codes (such as P0544 or P2080) and using a scan tool to verify the sensor's temperature readings are changing. Replacing a seized EGT sensor often requires applying heat with a torch and using specialized sensor sockets.