The Differential Pressure Feedback Exhaust Sensor, or DPFE sensor, is part of the vehicle's exhaust gas recirculation (EGR) system. The sensor monitors and measures the pressure with the EGR valve. This prevents the valve from malfunctioning and allowing too much exhaust into the intake manifold at one time. If a vehicle's running poorly or having poor gas mileage, the DPFE sensor may be to blame.
Open the bonnet of the vehicle. Locate the DPFE sensor, which is near the EGR valve, behind the upper intake manifold, between the firewall and engine. The sensor is a small square with two vacuum hoses on the bottom and a wire harness coming out from the side. The location will vary slightly from make and model. Check your repair manual for exact location and a detailed diagram.
Disconnect the two vacuum hoses from the sensor by giving them a firm tug.
Turn the ignition key to the "On" position. Do not turn the engine off. You want the sensors to run and PCM to turn on, but the engine to remain off.
Connect the negative (black) multimeter lead to a ground point, such as the negative battery terminal. Clip the positive (red) lead to the DPFE sensor signal wire. The sensor has three wires; the signal wire is the first wire on the left of the unit.
Allow the multimeter to register the voltage. Ford DPFE sensors should read between .45 and .55 volts. All other makes should read between .8 and 1.0 volts. If the sensor is not within the appropriate range, the sensor is faulty and should be replaced.