Where is the DPFE?

Discussion in 'Gen 3 Prius Technical Discussion' started by anonymous, Jul 22, 2018.

  1. anonymous

    anonymous Member

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    Does anyone know where in the EGR system the differential pressure sensor is located? Is it before or after the EGR valve? Or integrated in it? Or does it even have one? If not, how does it detect the gas flow?
     
  2. Raytheeagle

    Raytheeagle Senior Member

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    There are several sensors in the air flow:
    • Mass air flow sensor (MAF) on the inlet air side
    • Manifold Absolute Pressure sensor (MAP) near the throttle plate
    Did you get a P0401 code?

    Something else you are looking for?

    Good luck and keep us posted.
     
  3. ChapmanF

    ChapmanF Senior Member

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    I don't have your direct answer, but one of the technical manuals for the car, called the New Car Features manual, is the one that lays out the components and the principles of operation of each system in the car.

    -Chap
     
  4. anonymous

    anonymous Member

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    I'm just wondering how exactly the system detects an insufficient flow to throw the P0401. I read that the EGR (maybe) has a DPFE sensor for that. But maybe it doesn't have one; maybe it somehow detects flow using the EGR valve? It has like six wires.

    Because I'm wondering if having the EGR's valve input open (no EGR cooler) will suppress P0401. If there's no sensor before the valve then I think it could.
     
  5. Raytheeagle

    Raytheeagle Senior Member

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    There is no sensor, but the valve is activated and can get stuck by carbon buildup ;).

    I’d work on getting the while egr circuit cleaned and actuate the egr valve by removing the black cap and push on the plunger.

    Should buy you some time until the thorough cleaning(y).
     
  6. padroo

    padroo Senior Member

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    How many miles do you have on your Prius?
     
  7. anonymous

    anonymous Member

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    just over 200,000; guess I should put that in my signature :p

    -------------------------------------

    I currently have the EGR valve (after being cleaned) in without the EGR cooler while that is out for cleaning, and so far (after clearing codes) the check engine light hasn't come back. I put the valve back in yesterday and drove multiple times totalling maybe 20 miles. So it seems you can evade a P0401 just by letting the valve suck in fresh air. But I still wonder HOW the system detects a lack of flow to throw a P0401, given that there is no sensor… It must be sensing from the valve then; maybe it feels the resistance against opening the valve? So perhaps that's why people suggest taking the cap off and actuating the shaft to loosen it up; maybe the P0401 could just be caused by a stiff shaft......... :confused:

    BTW I did pop the cap a while ago when the p0401 issue arised and the shaft actuated perfectly smoothly
     
    #7 anonymous, Jul 23, 2018
    Last edited: Jul 23, 2018
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