P0401, P0402, Moisture and the DPFE

[gmtorque]

I have a 96 Explorer 4.0 with 162,000 miles. I am on the 3rd replacement DPFE sensor. In February I had a p0401 and p0402 at 154k with the original metal Ford sensor. I replaced it with a new plastic one from Advance Autopart, the part number is egr155 it is a BWD sensor which fixed the problem for a couple months. In April at 157k I got a p0402 and tested the sensor and found it to read between 4-5 volts with the key on engine off. I went and got a replacement free of charge and have been good for several months this time. Yesterday at 162k the light came on and again it was a p0402 so I tested the sensor with KOEO and the voltage was 4.68 volts. So I went to Advance and got another free sensor for the defective one. Truck is now fine again for a few months.

For those wondering the brown/green wire is the one being tested with a voltmeter on DC and grounding to the negative on the battery. From what I have read anything over .55v on the original sensor or 1.0v on the replacement sensors means the part is no good.

One thing that seems to be the major issue is water I have noticed everytime that the sensor is full of water and I am sure that is the reason for the failure. Since 90% of my driving is short trips I am pretty sure this is one reason my sensors don't last too long. I wonder if the OEM Ford part holds up longer? The only problem is I don't want to spend the money for a new Ford sensor. I am going to try having my wife take the vehicle once a week on a 40 minute trip she takes every week. Maybe that will help get the moisture out the sensor each week.

 

[robertoa1a]

I hope those were under warranty. Is it coolant or water getting in there? Is the DPFE getting too hot? Maybe there is un burned fuel in the exhaust. Any popping?

 

[jremington59]

I have read there is a plastic sensor and one made with metal. The metal ones seem to cause the problems. Do you buy the metal one?

 

[gmtorque]

The moisture is just water from the exhaust there is no fuel or antifreeze in it. The DPFE never feels hot when this happens. And yes I got all but the first one free since I claimed they are defective which is half true. I really think it is partially from a defective design that lets all that moisture collect in them.

The sensor I keep putting in is the plastic one. The original one was metal and lasted for 150,000 miles.

 

[robertoa1a]

This the first I have heard of this problem (multipul DPFE's in a short time). In the origonal isue I thought it was heat that was causing electronic failure. What are the odds of getting several bad ones in a row? It's the heat and miosture. Is there a hole in the exhaust tube or anything? I have an old one. Im going to cut it open and try to see what makes it tick.

 

[robertoa1a]

There's a lot of corrosion in there

It looks like a microphone in both sides and the gas can't go from one side to the other. If one of the gaskets gets week then gas gets to the electronics. A backfire could provably cause this. Is all of your normal tune op stuff up to date?

 

[gmtorque]

Yea everything works perfect and the truck runs like new. All tune up stuff is perfect.

Like I said I think that since all my trips are short 5 miles or less I think this contributes to the excessive water build up in the sensor.

 

[robertoa1a]

That water is getting hot in there. Is one of the tubes cloged?

 

[WayneBS]

I have the same problem with my 2000 Ranger XLT 3.0L. The CEL comes on with codes P0401 most frequent and P402 occasionally. I have replaced the DPEF sensor four times in 80K miles. The original metal one lasted about 42K the 1st replacement (plastic) lasted about 30K and the 2 recent replacements, less than 2K miles. All have failed the voltage tests that determines good or bad. I have replaced the EVR twice and the hoses most recently. I have removed the pipe and cleaned it and tested for leaks with no problems detected. While doing this, the ports at EGR valve and exhaust side were also cleaned. The EGR valve tests good. Vacuum lines are clear and functioning properly. Any suggestions?