EGR Valve Position Sensor: Description and Operation

The EGR pintle position sensor is potentiometer used to indicate the amount of EGR valve opening. The PCM supplies the pintle position sensor with a 5 volt reference and a ground. The pintle position sensor provides a signal voltage to the PCM. By monitoring the voltage on the signal line, the PCM is able to determine if the EGR valve responds properly to commands from the PCM. As the EGR valve position changes, the pintle position signal voltage will change. With the EGR valve closed, the signal voltage is near 0 volts. However, the pintle position signal voltage increases as the EGR valve opens. When the PCM commands the EGR valve fully open, the pintle position signal voltage should be above 4 volts. If the PCM detects an excessively low pintle position signal voltage (circuit is open or shorted to ground), DTC P0405 will set.

When the ignition switch is in the RUN position, the PCM learns the EGR closed valve pintle position. When the PCM commands the EGR valve closed, the PCM compares the closed valve pintle position to the actual EGR position. If the actual EGR position indicates that the EGR valve is still open, DTC P1404 will set.

The PCM controls the EGR valve using an ignition voltage driver and ground located within the PCM. When the PCM commands the EGR valve open, the PCM compares the actual EGR position to the desired EGR position. If the actual EGR is less than the desired EGR by a calibrated amount, DTC P0404 will set. If an electrical malfunction occurs in the EGR valve control circuit, DTC P0403 will set.