EGR Temperature Sensor: Description and Operation

EGR Temperature Sensor Circuit:

PURPOSE
The EGR Temperature Sensor, located on the EGR valve, verifies EGR valve operation. This is done by monitoring the exhaust passage temperature down stream of the EGR valve.

OPERATION
To confirm that the EGR valve is functioning properly the ECM expects to see an increase in temperature at the sensor whenever the EGR valve is operating. In the event of a malfunction the ECM will set a code and turn the Check Engine Light "ON". The resistance value of the sensor increases as temperature decreases.

Five volt power supply in the engine control module is applied to the EGR temperature sensor through the resistance in the unit. This power supply further passes through the EGR temperature sensor, which is a kind of a resistor, and is grounded at the engine control module. The resistance of the EGR temperature sensor is characterized by a decrease in resistance with an increase of EGR temperature due to increase in quantity of EGR.

EGR temperature sensor terminal voltage increases or decreases with EGR temperature sensor resistance. Therefore, EGR temperature sensor terminal voltage changes with EGR gas temperature. The higher the EGR gas temperature, the lower the EGR temperature sensor terminal voltage.