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How to: Diagnosing DPFE Sensor (P0401 and P0402) with Scan Tool

Discussion in 'Tips and Technical Info posted by Technician's' started by ExplorerDMB, August 10, 2006.

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    1. Tony H

      Tony H Well-Known Member

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      Thanks. No current issues, just trying to educate myself for future issues.
       
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    3. 2001Ranger

      2001Ranger New Member

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      What else?

      I've been reading the earlier posts on this subject. I have already replaced the DPFE in my 2001 Ranger. I still get the dual P0401/P0402 check engine codes. What else can it be? Someone suggested that it might be the catalytic converter or the O2 sensors. Any suggestions? Thanks

      2001Ranger
       
    4. BrooklynBay

      BrooklynBay Moderator & long time member. Staff Member Moderator Elite Explorer

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    5. 2001Ranger

      2001Ranger New Member

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      thanks

      Hi, thanks for the welcome and the suggestion. I R&R the EGR and flushed/cleaned the valve, vacuum hoses, and exhaust tube? with carb cleaner and dried it out. I reset the check engine light and after the 3 starts it came right back on. Any more ideas? thanks. 2001Ranger
       
    6. USS RIGHTEOUS

      USS RIGHTEOUS New Member

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      Hey I just put in a new engine and used all my old sensors. The old engine had a mega blown head gasket. I now have codes for my DPFE. Gee do you think that the blown head gasket could have introduced a little bit of moisture? Thanks for the good info!! :thumbsup: :D
       
    7. bizwiz79

      bizwiz79 New Member

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      2 Questions

      New member. Glad to be here. I have a few questions...

      1. Where is the DPFE sensor located on a 97 Explorer 5.0? Can't find it for the life of me! I have a bad feeling I have to pull the intake to get to it, though...

      2. After I change the DPFE, how long do I have to drive before it resets? If I reset the code manually, how long before the P1000 clears out?

      Thank you!
       
    8. X-North

      X-North Active Member

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      I got a 33 code code in my 1992 Explorer. I have the first slow 1-1-1 and then a faster 1-1-1 code ..a wait and it repeat the slow 1-1-1 and repaeat the faster 1-1-1. So thats why i think i have a 33 code. It give me a EGR code but where is located the EGR on a 1992 4.0 OHV..i dont see it. Thank you.
       
    9. elliswife

      elliswife New Member

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      dpfe

      SO... how does one swap out the old sensor for a new one when the plugs seem to be differently shapped? New plug is ovalish where as new one is not... explain?
       
    10. BrooklynBay

      BrooklynBay Moderator & long time member. Staff Member Moderator Elite Explorer

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    11. elliswife

      elliswife New Member

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      Dpfe

      No the plug in the picture on napa is OVAL shaped where as the old one looks like it's different shaped? Have you changed on of these from an original OEM part to a new OEM spec'd aftermarket?
       
    12. Fifty150

      Fifty150 Active Member

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      I just got the P0402 code @ 199,300.
       
    13. cjp_xsport

      cjp_xsport New Member

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      sounds like you have a different DPFE than the original. I swapped mine out on my 2002 sport about three years ago after receiving a CEL. I bought a Ford DPFE to replace. No worries.
       
    14. elliswife

      elliswife New Member

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      My explorer is Gen 1... any difference in the old sensor versus the new plastic one though?
       
    15. cjp_xsport

      cjp_xsport New Member

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      Likley...

      I checked my Haynes repair manual and it indicates two different pressure feedback EGR systems implemented on Explorers. The manual states "All 1995 and earlier models and 1996 5.0L V8 models are equipped with the Pressure Feedback Exhaust Gas Recirculation (PFE) system." And it goes onto say "1996 and later models (except 1996 5.0L V8 engine) are equipped with the Differential Pressure Feedback EGR (DPFE) system.".

      The manual shows two diagrams of the feedback systems and the block diagram for the older (i.e., pre-1996) shows the PFE valve only having one orifice to monitor pressure. The diagram for the newer DPFE system shows the valve having two orifices to monitor pressure.

      If this information is accurate, then to answer your question, I would hazard a guess the old (PFE) and new (DPFE) sensors are different. Do you have the old and the new plastic sensor available to look at? Are they different?

      I know there are smarter guys on this forum that have hands-on experience with these systems. My experience is only with the new DPFE on my 2002 Sport (also replaced it on my 2001 Focus).

      Good luck.
       
    16. elliswife

      elliswife New Member

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      Mine also has two lines into it...so confused.
       
    17. elliswife

      elliswife New Member

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      Mine also has two lines into it...so confused.
       
    18. cjp_xsport

      cjp_xsport New Member

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      Sorry elliswife...I'm confused a bit now as well. Guess the Haynes manual is a bit misleading in this area for the older ex's.

      The DPFE I replaced on my '02 was the same as the DPFE I replaced on my 2001 Ford Focus...both were plastic housings with connections to small diameter hoses. I remember when I was researching a CEL issue on my Focus that the guys on the Focus forum listed links to an older DPFE...I'll try to look for those links again to see if they might shed some light on this...I'm not expecting much out of this...

      Again, sorry for wasting your time...
       
    19. cjp_xsport

      cjp_xsport New Member

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      elliswife...have you checked with your local Ford dealer to see if they offer a wiring harness adapter for the updated DPFE sensor?
       
    20. elliswife

      elliswife New Member

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      No I haven't actually... I know the local "parts stores" don't list it.
       
    21. elliswife

      elliswife New Member

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      No time waste... it's a mission to figure out a lot of things on these rigs. Exploder=8th Wonder of the World. Even Ford mechanics admitt it (I used to work at a stealership as a receptionist).
       
    22. N182NS

      N182NS New Member

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      Diagnosing DPFE Sensor

      I had a 96 Explorer and just bought an 02 last year, I had to replace it on both. My diagnosing is as follows: disconnect vaccum hose for egr valve with engine running apply vaccum to the egr valve, if the engine runs rough or tries to kill then the valve is working and their is no blockage and the egr valve is good. Replace sensor. thanks :salute: Nick
       
    23. Allcruisen

      Allcruisen New Member

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      Checking Voltage on my Plastic DPFE? On the left, I have the three prongs. From where to where am I supposed to check Voltage, using an Amprobe Volt meter?

      Is the ign. switch to be on?

      Also, Is there a way to convert from the one on the fire wall to the smaller one, via changing the plug? Which wire would go were?

      Sorry for all the questions, its just I cant see myself paying $146.00 Dollars at the Stealership...

      Thanx in advance,
      Allcruisen

      PS Great Write up :thumbsup: :salute:
       
      Last edited: March 21, 2008
    24. l1tech

      l1tech New Member

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      That works well for testing the actual egr valve but what about testing the solenoid that controls the vacum to the egr valve, what about testing for vacum to the solenoid and last but not least what about testing for the pcm's ability to control the vacum solenoid.
       
    25. andysride

      andysride New Member

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      monitor dpfe reading on scan tool ,apply vacuum to the egr valve at idle engine should stumble indicating egr is working. check reading on scan tool if it doesn't change its the dpfe sensor. nice easy check .
       
    26. KPT

      KPT Well-Known Member

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      The manual is incorrect here. My 95 has a DPFE. Stock was the metal casing. I replaced it with an autozone part and it failed again a year or two later. Got a genuine ford DPFE, it was the updated plastic part with a wiring harness, cut and soldier deal.... Hasn't failed yet.


      Its on the back of the intake manifold. Towards passenger side, right next to the EGR. Pain in the ASS to change, you have maybe an inch to work in.

      Oh and OBDI will troubleshoot DPFE failures better than OBDII. My brother owns a 2000 5.0, I forget the exact codes but it was throwing a insufficient EGR flow. Took that DPFE off the 5.0, put it on my 4.0 (long after I had soldered on the new wiring harness). I drove maybe a mile and a half. MIL was not illuminated but I checked the codes anyway, had thrown a EGR pressure is/was out of range.
       

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