How to Troubleshoot a Ford Windstar DPFEby Don Bowman
The differential pressure feedback (DPFE) for the exhaust gas recirculation (EGR) sensor on the Ford Winstar is located in the center of the engine, close to the number 1 cylinder. This sensor has two input hoses that it uses with a fixed orifice to sense differential exhaust pressure and responds to these changes by sending various signals to the computer for the operation of the EGR. The voltage signals vary from .20 volts to 4.5 volts. If the hoses become plugged or if there is a failure of the electrical aspect of the sensor, the computer will respond by setting a code for this and turning on the "check engine" light.
Locate the DPFE and pull the two hoses off the bottom of the sensor. Look into the hoses for corrosion. The majority of the time, the hoses become clogged with a whitish powder from the exhaust. When this happens, the sensor no longer sees pressure from one or both hoses and fails. Bend the hoses and shake the dirt out of the hose. Remove the hose completely, if necessary to clean, by simply pulling it off the bottom metal line. If possible, leave the bottom side of the hose on because it is hard to reach to reinstall. Once the hoses are cleaned out, push them back on and start the engine.
Plug the code scanner into the on-board diagnostic (OBD) port under the driver's side of the dash. Push the "Erase" button, and the "check engine" light will go out. Unplug the code scanner.
Check the sensor for the proper voltage with the engine running. The electrical connector has three wires. Standing in front of the vehicle looking at the sensor and electrical connector, the terminal to the far right is the signal wire, the center is the negative ground wire, and the far left is the 5-volt supply voltage. If the hoses were plugged up, the odds are that was all that was wrong with the sensor; however, check for a signal to be sure it is working. If the hoses are clear and there is no signal, replace the sensor.
Turn the voltmeter to the 20-volt range and probe the far right terminal for .20 volts at an idle. Have someone help by raising the rpm slightly while you watch the voltmeter, to make sure the voltage begins to rise and fall with the rpm. If there is no signal or it does not change, check the center terminal for 100 mV or less on the scale. The sensor is shorted out if there is a higher voltage.
Check the far left terminal for five volts. This is the power supply, and if the voltage is wrong, there is a problem with the wiring between the computer and the sensor. If the sensor has power and no signal, or the center negative shows too much voltage, replace the sensor.