EGR Backpressure Transducer: Description and Operation

Purpose
The Differential Pressure Feedback EGR (DPFE) Sensor outputs a voltage proportional to the pressure drop across the metering orifice and supplies it to the PCM as EGR flow rate feedback.

Operation
When the vacuum signal applied to the EGR valve becomes sufficient to overcome the EGR valve spring force, the valve begins to open allowing exhaust gases to enter the intake system. This flow of EGR gases must also pass through a metering orifice located in the orifice tube assembly.

The DPFE sensor picks up the differential pressure signal across the orifice, and provides the PCM with an analog signal as feedback information on the rate of EGR flow. The PCM uses this feedback to adjust the EGR vacuum regulator duty cycle and achieve the desired EGR flow.

Construction
The DPFE is a ceramic capacitive type pressure transducer.