EGR Temperature Sensor: Description and Operation

The EGR gas temperature sensor is used to provide the ECM with information about EGR valve operation. When the EGR valve is open, exhaust gas heats the sensor. When the valve is closed, the sensor cools. The ECM monitors this temperature change and memorizes the range across which the temperature varies under normal operation. If the ECM detects a temperature range smaller than that stored in memory (approx. 6°C / 11°F), it senses a fault. If the fault is noted on three consecutive measurements, a trouble code will set. Measurements are taken when conditions exist such that the ECM "knows" the EGR valve should be either fully open or fully closed.

The ECM detects changes in sensor resistance that vary with temperature as follows:

Temperature °C(°F) Resistance (K ohms)

0 (32) 28
20 (68) 12.1
40 (109) 5.8
80 (176) 1.7
100 (212) 1.0