EGR DPFE Sensor story
Question:
FYI for everyone regarding the EGR DPFE (Differential Pressure Feedback EGR) sensor. 1996 Explorer XLT, v6, 4 Liter Got a Check Engine light a few weeks ago. Noticed nothing wrong with engine performance, except occasional pinging at high loads on highway about 70MPH, on hot days. Back off to about 60 MPH, all OK. Code puller showed P0401, which is generic code for "EGR insufficient flow detected" (I bought an Equus code reader – $125 at Summit Racing in Akron, OH). After doing the diagnostics recommended in the Haynes manual, it turned out the DPFE sensor was bad. It’s the aluminum block with the two black hoses coming out the bottom, and the electrical connector. Per Haynes, I backprobed the SIG and GND terminals, while it was plugged in with engine running. SIG is the top terminal, GND is the middle. I backprobed them by snapping off that little plastic guard where the three wires go in, and pushing in a thin 3/4" long brad until only about 3/16" showed. That was enough to get contact with the metal tab inside. Haynes says it should be 0.35 to 0.8 volts with engine running, cold. It says when it warms up it should go to betwen 4 – 6 volts as EGR is requested by the PCM. Mine was stuck at 1.55 volts, with no variation at all, regardless of temperature or engine load, so I deduced that it was bad. BTW, I put red on the top backprobed terminal brad, and used one of the brake lines from the ABS as my GND (instead of risking shorting them together at the connector). I did test the EGR valve with a vacuum pump/guage and it actuated fine starting at 1" – 2" of Hg or less, and held vacuum. Also fiddled with the EGR vacuum regulator solenoid, and it tested fine per Haynes (should have 12v at the connector when ignition on, and the resistance of the solenoid should be between 30 and 50 ohms (I got 43). So I went out and go a new DPFE sensor at AutoZone, for about $57 out the door. Put it on and it seems to work fine. I rigged my voltmeter so I could drive around and monitor the sensor’s output based on engine load. It constantly varied between 0.65 and 2.5 as I drove, which I say is fine (the other one stuck at 1.55 and didn’t move). The Check Engine code never came back, so I think this did the trick Supposedly these EGR DPFE gadgets fail commonly. I pulled out the brads and snapped the lead protector thingy back on. I took the old one and drilled/punched out the six rivets. When I pulled it apart and lifted out the white sensor module, it was loaded up on both sides internally with close to a half teaspoon of granular gunk. Looked like coarse sand, gray and off-white particles. Likely just ash and gunk, possibly precipitated crystals or oxides or something. Anyway, the sensor chambers were pretty gunked up with this stuff. That explains why the sensor was reading bad, thus giving bad info to the PCM which probably ultimately wound up causing my ping. I’ll probably also clean the MAF which is recommended, and also tightening down the lower intake manifold bolts. Hope this helps someone else. Thanks to all those others on this NG who provided help to me during my diagnosis. Mike
Response:
- Hide quoted text — Show quoted text – >FYI for everyone regarding the EGR DPFE (Differential Pressure Feedback EGR) >sensor. 1996 Explorer XLT, v6, 4 Liter >Got a Check Engine light a few weeks ago. Noticed nothing wrong with engine >performance, except occasional pinging at high loads on highway about 70MPH, >on hot days. Back off to about 60 MPH, all OK. >Code puller showed P0401, which is generic code for "EGR insufficient flow >detected" (I bought an Equus code reader – $125 at Summit Racing in Akron, >OH). >After doing the diagnostics recommended in the Haynes manual, it turned out >the DPFE sensor was bad. It’s the aluminum block with the two black hoses >coming out the bottom, and the electrical connector. Per Haynes, I >backprobed the SIG and GND terminals, while it was plugged in with engine >running. SIG is the top terminal, GND is the middle. I backprobed them by >snapping off that little plastic guard where the three wires go in, and >pushing in a thin 3/4" long brad until only about 3/16" showed. That was >enough to get contact with the metal tab inside. >Haynes says it should be 0.35 to 0.8 volts with engine running, cold. It >says when it warms up it should go to betwen 4 – 6 volts as EGR is requested >by the PCM. Mine was stuck at 1.55 volts, with no variation at all, >regardless of temperature or engine load, so I deduced that it was bad. >BTW, I put red on the top backprobed terminal brad, and used one of the >brake lines from the ABS as my GND (instead of risking shorting them >together at the connector). >I did test the EGR valve with a vacuum pump/guage and it actuated fine >starting at 1" – 2" of Hg or less, and held vacuum. Also fiddled with the >EGR vacuum regulator solenoid, and it tested fine per Haynes (should have >12v at the connector when ignition on, and the resistance of the solenoid >should be between 30 and 50 ohms (I got 43). >So I went out and go a new DPFE sensor at AutoZone, for about $57 out the >door. >Put it on and it seems to work fine. I rigged my voltmeter so I could drive >around and monitor the sensor’s output based on engine load. It constantly >varied between 0.65 and 2.5 as I drove, which I say is fine (the other one >stuck at 1.55 and didn’t move). The Check Engine code never came back, so I >think this did the trick Supposedly these EGR DPFE gadgets fail commonly. >I pulled out the brads and snapped the lead protector thingy back on. >I took the old one and drilled/punched out the six rivets. When I pulled it >apart and lifted out the white sensor module, it was loaded up on both sides >internally with close to a half teaspoon of granular gunk. Looked like >coarse sand, gray and off-white particles. Likely just ash and gunk, >possibly precipitated crystals or oxides or something. Anyway, the sensor >chambers were pretty gunked up with this stuff. That explains why the >sensor was reading bad, thus giving bad info to the PCM which probably >ultimately wound up causing my ping. >I’ll probably also clean the MAF which is recommended, and also tightening >down the lower intake manifold bolts. >Hope this helps someone else. >Thanks to all those others on this NG who provided help to me during my >diagnosis. >Mike
Thoughtful and systematic diagnosis found the problem and fixed it the first time. What a relief that out there somewhere someone still looks for the problem instead of throwing parts at the car until, somehow he swaps out the offending one. Congratulations!
Response:
Wow. I’ll have to go get my old one and open it up. I’ve been meaning to do that, just haven’t had the time. – Hide quoted text — Show quoted text – > I took the old one and drilled/punched out the six rivets. When I pulled it > apart and lifted out the white sensor module, it was loaded up on both sides > internally with close to a half teaspoon of granular gunk. Looked like > coarse sand, gray and off-white particles. Likely just ash and gunk, > possibly precipitated crystals or oxides or something. Anyway, the sensor > chambers were pretty gunked up with this stuff. That explains why the > sensor was reading bad, thus giving bad info to the PCM which probably > ultimately wound up causing my ping.
Response:
As a licenced tech, I must also heartily congratulate Mike. He has used sound diagnostic procedures to rectify his problem. The only question that bears asking is how much Mike (or anyone) would be willing to pay for this kind of service. Mike, from the sound of it, is a cut above most DIYers (sorry guys) and appears to be gaining a handle on just what this job is all about…. — Jim Warman – Hide quoted text — Show quoted text ->FYI for everyone regarding the EGR DPFE (Differential Pressure Feedback EGR) >sensor. 1996 Explorer XLT, v6, 4 Liter >Got a Check Engine light a few weeks ago. Noticed nothing wrong with engine >performance, except occasional pinging at high loads on highway about 70MPH, >on hot days. Back off to about 60 MPH, all OK. >Code puller showed P0401, which is generic code for "EGR insufficient flow >detected" (I bought an Equus code reader – $125 at Summit Racing in Akron, >OH). >After doing the diagnostics recommended in the Haynes manual, it turned out >the DPFE sensor was bad. It’s the aluminum block with the two black hoses >coming out the bottom, and the electrical connector. Per Haynes, I >backprobed the SIG and GND terminals, while it was plugged in with engine >running. SIG is the top terminal, GND is the middle. I backprobed them by >snapping off that little plastic guard where the three wires go in, and >pushing in a thin 3/4" long brad until only about 3/16" showed. That was >enough to get contact with the metal tab inside. >Haynes says it should be 0.35 to 0.8 volts with engine running, cold. It >says when it warms up it should go to betwen 4 – 6 volts as EGR is requested >by the PCM. Mine was stuck at 1.55 volts, with no variation at all, >regardless of temperature or engine load, so I deduced that it was bad. >BTW, I put red on the top backprobed terminal brad, and used one of the >brake lines from the ABS as my GND (instead of risking shorting them >together at the connector). >I did test the EGR valve with a vacuum pump/guage and it actuated fine >starting at 1" – 2" of Hg or less, and held vacuum. Also fiddled with the >EGR vacuum regulator solenoid, and it tested fine per Haynes (should have >12v at the connector when ignition on, and the resistance of the solenoid >should be between 30 and 50 ohms (I got 43). >So I went out and go a new DPFE sensor at AutoZone, for about $57 out the >door. >Put it on and it seems to work fine. I rigged my voltmeter so I could drive >around and monitor the sensor’s output based on engine load. It constantly >varied between 0.65 and 2.5 as I drove, which I say is fine (the other one >stuck at 1.55 and didn’t move). The Check Engine code never came back, so I >think this did the trick Supposedly these EGR DPFE gadgets fail commonly. >I pulled out the brads and snapped the lead protector thingy back on. >I took the old one and drilled/punched out the six rivets. When I pulled it >apart and lifted out the white sensor module, it was loaded up on both sides >internally with close to a half teaspoon of granular gunk. Looked like >coarse sand, gray and off-white particles. Likely just ash and gunk, >possibly precipitated crystals or oxides or something. Anyway, the sensor >chambers were pretty gunked up with this stuff. That explains why the >sensor was reading bad, thus giving bad info to the PCM which probably >ultimately wound up causing my ping. >I’ll probably also clean the MAF which is recommended, and also tightening >down the lower intake manifold bolts. >Hope this helps someone else. >Thanks to all those others on this NG who provided help to me during my >diagnosis. >Mike > Thoughtful and systematic diagnosis found the problem and fixed it the > first time. What a relief that out there somewhere > someone still looks for the problem instead of throwing parts at the car > until, somehow he swaps out the offending one. > Congratulations!
Response:
Categories: 1996 Explorer | 
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. My biggest gripe is lack of a headrest if you’re tall. God help me in a rear collision. But to get the headrest, you need the Limited seat which is an overstuffed Barcalounger (sp?). Both not real attractive and unsupportive. To answer your question, I think any power seat should work with your XLT as long as it has power. My recommendation would be for a 97 seat (EB or XLT) with the leg bolsters and perf leather. Depends really on your color too. Most EBs had tan (although mine has grey), but the ONLY difference between a sport bucket in an EB and an XLT is the embroidered logo. The only benefit I see with the Limited seats are the headrest, and they’re too far back to do any good anyways. JH 95 EB – 134K miles – Hide quoted text — Show quoted text -> One more question. After a year, I really hate the seats in my ‘99 XLT. > They’re leather, but there is no back support (even with the lumbar > adjustment) and it just looks horrible. Airplane seats look better. I’m > thinking of finding a Limited or EB that has the different seats with an > actual headrest and switching. Anyone know if they’d fit and if the power > controls would connect to the XLT wiring? > Dean