Hello I have a P402 excessive recirculation exhaust gas detected. I have 97 with 162000 miles 4.6, I had a P401 awhile back which drove me crazy after I replaced everything the book said suggested that took be. I placed a post here and a ton a people told me about cleaning out the ports in the intake manifold (thank you all). After that life was good until yesterday P402. I placed a hand pump the 6 month old egr valve and exercised it , cleared trouble code, good to go. Drove to work and back today ran some errands then as I was parking it in the garage stupid P402. ?

 

Whenever at idle, the PCM checks the voltage of the DPFE sensor and compares it with the voltage recorded by the PCM during the last Key On Engine Off state.

If the voltage is different this indicates a gas flow where none should exist, and the PCM stores the DTC P0402 EGR Flow Excessive Gas Detected. This can cause confusion: in this context excessive flow means there is a flow where none should be detected, ie, the EGR poppet valve has stuck open.

That's what it means anyway, also -

When the EGR pipe is secure this is an effective test for the poppet valve in the EGR. Be aware however that if the EGR pipe is loose at the EGR end and exhaust gas can escape, then P0402 will be stored. The system has detected a gas flow but not through the EGR valve - gas is escaping from the pipe union with the EGR.

How many HG's did you put on the diagram with the pump ?

Idunno, there's better than 80% chance that you have a defective DPFE Sensor. Simply because, if you were stuck open, the truck would be running like sh^t.

Those DPFE's MUST be replaced with a Ford dealership ONLY unit. 3rd Party suppliers sell DPFE's that don't last long. For the 97 (aluminum DPFE only) - TOMCO sells a good one at a good price.

 

Thanks for info, snugged up the pipe to the EGR, as far as HG's right around six, I could hear the spring/diaphragm move. The truck is running good smooth at idle, oh I bought a after market DPFE sensor when I having issues with the P401 thing, it's piece of plastic. I knew I should have kept the original dang.I'll go to Ford in the day or so thanks a million.

 

Yea, didn't you have an aluminum one stock?

Two different sensors are in use, one metal cased and the other plastic. These sensors should not be interchanged - further, some sensors have a modified voltage output.

 

Yep real nice piece of machined aluminum.The hoses bearly reach the plastic after market one, thanks again.

 

Hey, I'm glad I'm not the only one with these EGR excessive issues. A couple of months ago my service engine light came on, EGR flow LOW. After reading a few posts I replaced the old aluminum dpfe sensor with a plastic one I bought at Crow Burlingame. I reset the computer, EGR flow LOW came back that day. I removed the throttle body and "elbow" and cleaned the ports that were almost completely obstructed with carbon build up. Service light went away for about a month but now it's back---EGR flow EXCESSIVE. Thinking that there might have been a problem with the EGR valve itself, I replaced it, reset the computer and the light came back on later that day (EXCESSIVE flow). I'm at a loss, should I try putting the old aluminum dpfe back in place?

 

Read two posts up , then get a new ALUMINUM DPFE at the dealership only. Use the search - it's really a great feature.

 

You're correct about getting the right sensor. Fortunately I kept the old aluminum sensor so when I put it back in, reset computer still no service engine light so I think the problem is solved. The original low flow was due to clogged ports in the throttle body elbow, ford sensor was good aftermarket=crap. Thanks for the help.

 

No problem, glad it worked out.

 

crap. you guys know how many boxes i have to climb over and search through to see if i have my oem alum housing dpfe?

 

I took my Aluminum dpfe sensor apart and found that the seal between the 2 sides (sensors) was contaminated. I drilled out rivits then cleaned aluminum seats and gaskets I then used silicone grease to seal the 2 sides then held assyembly together with clamps and tapped holes and inserted screws. I hope this works. I have fixed a lot of sensors and found out why many quit working and also found there was nothing wrong with the sensor.

 

That's why Ford switched to a plastic DPFE - the aluminum ones were corroding.

 

Yea , they can get pretty nasty inside after awhile. They get wet and yea, chucks of white rusty sludge get stuck in between the ceramic and rubber seal iside. The new one I'm running now is a year and half old. I looked at it about 6 months ago and no rust or corrosion - YET!





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My old one corroded so bad, there wasn't much aluminum left where you slide the hoses on lol.