This 2002 Ford Explorer came in with the complaint that the engine would run poorly or not at all. The customer stated that he was able to start the engine only after installing a new set of spark plugs. There were multiple codes stored in the PCM; P0113, P0123, P0453, P0708 and P1289.
Some of the erroneous data that I saw was EGR DPFE voltage at 5 volts without the engine running.
Intake air and coolant temperatures at -40 degrees F. TPS, IAT and CHT voltage at 5 volts.
Time to do some testing at the sensors. A 1/4 inch driver removes the retaining bolts for the top engine cover.
Checking the five volt reference signal on the brown/white wire found zero volts.
Checking voltage on the gray/red wire found a reading of .527 volts. It is what should be expected on the return circuit (sensor ground).
Having already looked at a wiring diagram, I went to the DPFE sensor to check the signals there. There is a thumb latch that has to be depressed to disconnect the harness from the sensor.
Also knowing that it is fairly common for the DPFE sensors to short out and drop the PCM’s 5 volt reference, I rechecked the voltage on the brown/white wire and the proper five volt signal was present. I reconnected the TPS and started the engine. It started but took a few minutes before it started to run okay.
Time to change the DPFE sensor. Since the harness is already disconnected the only thing left to do is to separate the two hoses from the DPFE sensor tubes. I use a large common screw driver to pry the hoses off of the tubes. Being sure not to damage the hoses.
The new sensor on the right is nearly twice as big as the original. In case you were wondering DPFE stands for Differential (Delta) Pressure Feedback EGR sensor. The PCM uses it to determine if the EGR valve has opened and flowed the proper amount of exhaust gases back into the intake.
While I do my best to detail as much information as possible. There are many repairs that I have yet to document and some of you may wish to have more than I have provided. I would strongly recommend subscribing to one or both of the following data companies for further assistance. Although having an abundance of information does not guarantee an easy repair, the lack of adequate information will guarantee a failed repair!
Need more information? Subscribe to Mitchell1 today!