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P0401 code help needed

Discussion in 'Gen 3 Prius Care, Maintenance & Troubleshooting' started by 2010_Prius_Bro, Jun 13, 2023.

  1. 2010_Prius_Bro

    2010_Prius_Bro Junior Member

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    I have tried to open the black cap of the original EGR valve but I am having the hardest time! The philips screws is just about to be stripped. I've spray some PB blaster but doesn't help. How do you even open these things? I wanna see the condition on the inside.
     
  2. ChapmanF

    ChapmanF Senior Member

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    Step away from it before you strip them. Visit the local hardware store for a "hand impact driver".

    [​IMG]

    This is a thing you hold with one hand, twisting it in the 'loosen' direction, and bop on the end with a hammer. The impact bops the bit down against the screw so it doesn't slip, and also twists in the direction you're turning.

    It normally just takes a couple bops to start these loose (and then they come out just as nice as you please), but they are very easy to strip and give yourself bigger headaches, if you don't use this tool.
     
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  3. 2010_Prius_Bro

    2010_Prius_Bro Junior Member

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    I have never seen this kind of tool before but it certainly makes sense. The impact of the hammer to prevent slippage with the concomitant counterclockwise twist is genius. I certainly will look to get purchase this tool! Thanks!
     
  4. Mendel Leisk

    Mendel Leisk Senior Member

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    Second time I had the valve in my hands I used an impact screw driver like that pictured above, did the trick. I also replaced the screws, with socket head cap screws. They were M5x16 (diameter x length in mm) IIRC. I’ll check and confirm.
     

    Attached Files:

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  5. mjoo

    mjoo Senior Member

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    What you need is an Impact Screwdriver

    moto g power ?
     
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  6. Mendel Leisk

    Mendel Leisk Senior Member

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  7. CR94

    CR94 Senior Member

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    I loosened those balky screws successfully using a Harbor Freight ratcheting right-angle screwdriver, which lets you apply a lot more torque than you can with a conventional straight screwdriver. It helped that the tip was new and sharp.


    I'd be wary of hammering too hard on them.
     
  8. 2010_Prius_Bro

    2010_Prius_Bro Junior Member

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    Mendel, there should have been socket screws to begin with. I guess Toyota designed it so that the cap would not be easily removed for whatever reason. I really like that wood spacer idea! That is ingenious! Please let us know the correct specs of the socket head cap screws. Thanks in advance!
     
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  9. Mendel Leisk

    Mendel Leisk Senior Member

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    I’m trying to post a &$%#£?! Amazon link, so far without success. I will prevail, might just have to post screen grabs.
     
  10. Mendel Leisk

    Mendel Leisk Senior Member

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    Yeah it’s M5x16, 50 pack for about $15 CDN currently.

    IMG_1393.jpeg
    IMG_1394.jpeg
     
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  11. Brian1954

    Brian1954 Active Member

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    Where in Maryland do you live?

    I own one of these impact tools and would let you use it to get the screws loose on the old EGR valve.

    Posted via the PriusChat mobile app.
     
  12. 2010_Prius_Bro

    2010_Prius_Bro Junior Member

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    Hey, I live just south of Baltimore.
     
  13. Brian1954

    Brian1954 Active Member

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    I live in York, PA.

    I think that we could work it out. This sounds like something that does not need to be done right now. I will send you a PM latter today.

    Posted via the PriusChat mobile app.
     
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  14. ChapmanF

    ChapmanF Senior Member

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    You don't hammer hard on them at all. Just a couple bops on the impact tool with the hammer.

    There is nothing massively stuck about these screws at all. There is a bit of initial stiction, which the impact tool surprises them out of, and then you can spin them out with your fingers.

    Once you see how easy it is with the right tool, any urgency to replace them with other types of screws or other types of heads just kind of evaporates.
     
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  15. Mendel Leisk

    Mendel Leisk Senior Member

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    The socket size on the heads is 4 mm, and due to adjacent evap line I needed to resort to a T-handle 4mm hex driver (I just happened to have), and it worked nicely. Very easy to break them loose or snug down.

    IMG_1399.jpeg
    (I did add washers.)
     
    #55 Mendel Leisk, Jun 19, 2023
    Last edited: Jun 19, 2023
  16. Paladain55

    Paladain55 Active Member

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    Another option if you don't need to pass emissions is to unplug the egr valve electrical connector and forget it exist. If you need to pass emissions, you need to get that valve replaced though.
     
  17. ChapmanF

    ChapmanF Senior Member

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    Or even if you care about emissions, whether or not you 'have to' pass them.

    Or if you're not sure you want to drive permanently with bad-EGR-fallback ignition timing.

    Or if you'd like to be able to use your check-engine light to know when the engine needs checked.
     
  18. C-in-DC

    C-in-DC Member

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    Is the egr disabled in power mode? Enabled in econ mode ?
     
  19. ChapmanF

    ChapmanF Senior Member

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    The engine control module doesn't even know which of those "modes" you're in. Those are just inputs to the power management control ECU (car's orchestra conductor), which also sees the go pedal input.

    It just uses those "modes" to change how it translates different amounts of pedal input to amount of power requested. (ECO mode also tweaks the HVAC some, but that's a different story.)

    [​IMG]

    All the ECM gets from the power management control ECU is a request for "please give x kW of engine power".
     
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  20. 2010_Prius_Bro

    2010_Prius_Bro Junior Member

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    I am back after being able to open an OEM EGR valve and aftermarket EGR valve made in China. I had to purchase an impact screwdriver to open the cap screws as they were very tight for both the OEM and aftermarket EGR valves! Here are pictures of the OEM EGR valve.

    EGR valve_1.jpg EGR valve_2.jpg EGR valve_3.jpg EGR valve_4.jpg