EGR Temperature Sensor: Description and Operation

EGR Temperature Sensor:

PURPOSE
The EGR temperature sensor monitors whether or not the EGR System is operating.

LOCATION
Near the EGR valve, threaded into the EGR passage.

OPERATION
The EGR Temperature Sensor is a negative temperature co-efficient thermistor. The greater the temperature the lower the resistance. The sensor is exposed to hot exhaust gas in the EGR passage under normal conditions and this heat will cause the sensor to change resistance. If the ECM reads no voltage change in the sensor circuit (from a short or open) it will store a trouble code for the sensor.

Note: When the ECM senses higher than expected voltage, it assumes that an EGR control (i.e. EGR valve or control solenoid) has failed. Voltage that is too high can also be caused by the sensor becoming coated with carbon and not heating up properly.