EGR Valve Position Sensor: Description and Operation

EGR Lift Sensor (typical):

PURPOSE
The Exhaust Gas Recirculation (EGR) lift sensor detects the amount of EGR valve lift and sends this information to the Engine Control Module (ECM).

OPERATION

The EGR Lift Sensor is a plunger operated potentiometer which is attached to the EGR Valve diaphragm. The resistance of the sensor is inversely proportional to the amount of vacuum the EGR Valve.
The sensor receives a 5.0 volt signal from the ECM. When vacuum to the EGR Valve is high, resistance of the potentiometer is low, which causes the return signal voltage to the ECM to be high. When no vacuum is being sent to the EGR Valve, resistance in the potentiometer is high, causing a low voltage signal to be returned to the ECM.