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I'm new to the forum and in need of some help. I have read some of the other posts concerning the P0401 DTC. I have a 2002 Explorer with 88K miles. I have had a Service Engine Soon light on for about 4 months. At times the light will go out on it's own however other times the battery has to be disconnected to get the light out. I replaced the DPFE (Wells brand, not Ford). That worked for about a week. I exchanged that DPFE for a new one and that one worked for about a week also. Same thing with the third try. I recently replaced the EGR valve. The light stayed off for about 2 days then came back on. Every time I disconnect the battery the light stays off for about a day or two. I noticed that every time I pull the DPFE off it has a small amount (a few drops) of water in it. Is this enough to cause the SES light to come on? What else should I do to correct the issue? Is there something else that could be causing the light?
yes, there is an orfic in the EGR tube and the DPFE straddles the orfice, registering the differencial pressure in the tube. If one of these tubes or the orfice is blocked it will throw a code and illuminate the MIL
All right. I pulled off the entire pipe going from the exhaust to the DPFE and EGR. It had no blockage and only a very small amount of carbon dust lining the sides. The small orafice tube however had some moisture in it. I disconnected the battery cable to reset the SES light. Again it worked for a few hours but the light came back on.
Can anyone think of anything else I can do to solve this issue?
2 things; put on a new FORD DPFE sensor; they carry a revised model that specifically addresses the issue. Other thing to check, run the EGR tests outlined in the service manual--you may have another component in the EGR system that is not working--perhaps the lift solenoid, etc.
I started another post concerning the 402 code, which could be the EGR or the DPFE or a clog.Have to get a wrench big enough to get the pipe fitting apart.