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[SOLVED] P0401 code....

Discussion in 'Gen 3 Prius Care, Maintenance & Troubleshooting' started by Atari, Jul 18, 2019.

  1. Atari

    Atari Member

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    Or maybe I should say [SOLVED....???]

    What's wrong with this picture?...

    [​IMG]
     
    #1 Atari, Jul 18, 2019
    Last edited: Jul 18, 2019
  2. bisco

    bisco cookie crumbler

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    missing lite bulb?
     
    #2 bisco, Jul 18, 2019
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  3. Ed Beaty

    Ed Beaty Active Member

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    Nicely focused.....on the asphalt. :p
     
    #3 Ed Beaty, Jul 18, 2019
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  4. Atari

    Atari Member

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    That's what I WAS thinking, that it was missing the element -- but now I'm not so sure. I guess I'll stop by Toyota and see what the part actually looks like for the Prius. Seems like on new MAP sensors, it is missing for Prius (so mine may be OK) but on other Toyota vehicles using the same MAP part package, an element/bulb is in there inside the cage.
     
    #4 Atari, Jul 18, 2019
  5. Atari

    Atari Member

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    You may not call me for your wedding photos, but you might call me if your "just married" vehicle breaks down on side of road? :p
     
    #5 Atari, Jul 18, 2019
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  6. Mendel Leisk

    Mendel Leisk Senior Member

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    Yeah there should be a little gizmo in the cage, looks like a resistor. I might be able to dig up a pic.

    They're not cheap btw, well over $200 (US).
     
    #6 Mendel Leisk, Jul 18, 2019
  7. Atari

    Atari Member

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    Check it out...

    Fits 2010-2013 Toyota Prius MAP Sensor Denso 47542XC 2011 2012 1.8L 4 Cyl | eBay

    (for those clicking the link a year later when this ebay auction is long gone, it depicts a NEW 2010-2013 MAP sensor without an element inside the cage)
     
    #7 Atari, Jul 18, 2019
  8. Atari

    Atari Member

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    At 16 minutes in, NutsAboutBolts removes the MAP sensor. You only get a few frames to see inside the cage, but it looks empty here too...



    @NutzAboutBolts
     
    #8 Atari, Jul 18, 2019
  9. Mendel Leisk

    Mendel Leisk Senior Member

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    I couldn't find a pic with the sensor in view, but pretty sure this is the back, with numbers. One hole is for hold-down bolt, the other for register pin:

    upload_2019-7-18_11-40-44.png

    89421-52010
     
    #9 Mendel Leisk, Jul 18, 2019
    Last edited: Jul 18, 2019
  10. Atari

    Atari Member

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    "Part Number "89421-52010" was found for Toyota, but we could not verify the part fits the selected vehicle."

    Probably fits Highlander though... and that part number definitely has the element in it.
     
    #10 Atari, Jul 18, 2019
  11. Mendel Leisk

    Mendel Leisk Senior Member

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    Just googling, mine looks like this:

    [​IMG]
     
    #11 Mendel Leisk, Jul 18, 2019
  12. Atari

    Atari Member

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    I will stop at Toyota on lunch (soon) and snap a pic of the new part (if they can even figure out what it's called on the 2010)
     
    #12 Atari, Jul 18, 2019
  13. cnc97

    cnc97 Senior Member

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    Rock auto shows a sensor with the resistor wire in place, but it says up to 10-2009, the sensor for 11-2009 and up shows no resistor wire. So the plot thickens so they say. LoL
     
    #13 cnc97, Jul 18, 2019
  14. wheezyglider

    wheezyglider Active Member

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    I know that my 2010 has the element, but when I went to reassemble our 2012 I was shocked to see the element missing. I did a similar image search and figured maybe this was an updated version. So I just put that MAP sensor back in the 2012 and it has been running fine.
     
    #14 wheezyglider, Jul 18, 2019
  15. RightOnTime

    RightOnTime Senior Member

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    From cleaning this MAP sensor at the shop, I noticed there are at least 2 different versions for the 2010 - 2015 Toyota Prius.

    Worse one that I dealt with occurred when the resistor was clogged up with oil gunk and I had to take a small tool to clean it out


    iPhone ?
     
    #15 RightOnTime, Jul 18, 2019
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  16. Atari

    Atari Member

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    UPDATE:

    NEVERMIND THE MAP DISCUSSIONS...


    It was the magnet and/or spring INSIDE the EGR...

    I bought EGR and cooler today from some nice guys in Rancho Cordova (Delta One Auto Dismantling 916-701-5911) and only had to use the Magnet, Spring and Cap. Probably could have used the old cap....

    [​IMG]

    Image above is from this video from John Caleb Warren's youtube channel:



    Long story short the magnet on mine, when wound all the way down, would STICK and not automatically unwind like the "new" one would. So rather than go through the hassle of removing the whole EGR and cooler (which I know are very clean)... I tried replacing just the magnet, spring and cap.... and it WORKED! :) No more P0401 after more than 35 miles after a reset.
     
    #16 Atari, Jul 20, 2019
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  17. Raytheeagle

    Raytheeagle Senior Member

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    That ones off of recycle road too:).

    That makes three good sources of salvage parts there:

    • HP Motors (they have aisle after aisle of Prii)
    • Benzeen Auto Parts (not as extensive, but they have stock)
    • Delta One Auto Dismantling (pretty sure they were Green Earth Auto Dismantling)
    Glad you got it sorted(y).
     
    #17 Raytheeagle, Jul 20, 2019
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  18. Atari

    Atari Member

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    An update to the update...

    I was curious exactly how the magnet thing had failed, so I played with the failed one a bit more, lubricated the bearings, tried a bunch of things. I'm pretty sure what happens is the plastic THREADS inside the magnet get damaged and allow the magnet to "jump" off track of the threads and screw on farther than it should allow, which allows the magnet to get tight enough to where it does not automatically unwind itself.

    TLDR: plastic threads inside magnet get stripped.

    If you want to go to dismantler prius EGR, you now know what to test to make sure the EGR works -- not just the plunger/valve, but also open it up and make sure the magnet unwinds on its own and doesn't get stuck.
     
    #18 Atari, Jul 22, 2019
    Last edited: Jul 22, 2019
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  19. ASRDogman

    ASRDogman Senior Member

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    You can get to that nut with a SnapOn 1/4 drive with a wabbly extension. You don't need to remove the wiper assembly.
    When I cleaned my egr circuit I loosened and removed everything I could easily access before removing the wiper assembly.
    That egr cooler was clogged and should have been removed and cleaned. He could have used either carb or brake cleaner
    to clean and loosen the egr valve. Then he only needed to replace the magnet, if that was bad.
     
    #19 ASRDogman, Jul 22, 2019
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