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P0402 EGR Excessive Flow

Discussion in '4 Cylinder' started by vapovick, Sep 1, 2011.

  1. vapovick

    vapovick [OP] Active Member

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    Ok, so I got the 402 code, pulled the EGR valve and the thing was really dirty, based on other reviews, cleaning it may damage the diaphragm. So I replaced it. Brand new 142.00, code was cleared of course because I disco'd the neg terminal. a week later, P0402 re-appeared. I pulled the MAF sensor, sea foamed it, new air filter. Of course, it cleared again due to the neg terminal being removed, After a week it popped the code again.

    So I did the following.

    1) checked the check valve for proper operation, it passed OK
    2) checked the EGR vacuum modulator, it passed OK
    3) Engine off for about an hour, I checked OHMS as the EGR temp sensor.
    with the meter set at 2000k, I read 100 OHMs, with the meter set at 20k, i get 0. I believe anything under 200OHM's shows a short. Can someone advise if I have tested this correctly?

    I tried to pull the EGR temp sensor, and its really in there, I sprayed some PB blaster, let it soak, but still having issues, a 13mm doesnt fit, and a 14mm seems to have a little play. After some discussion I think i need to let it sit over night with some PB blaster soaking in, and then give it a try, but this is another 152.00 part, and I curious if this is the issue.

    Speaking to a Toyota tech, he said, they always replace both the EGR valve and the temp sensor.

    Wanted to see what you guys thought.


    Thanks for any help
     
  2. vapovick

    vapovick [OP] Active Member

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    anyone have any ideas?
     
  3. vapovick

    vapovick [OP] Active Member

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  4. 98tacoma27

    98tacoma27 :POOPCORN: Staff Member

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  5. ao6902

    ao6902 Well-Known Member

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    Based on the testing you did and what the toyota tech said, replace the temp sensor.
     
  6. vapovick

    vapovick [OP] Active Member

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    Ok, well I changed the sensor, and the light is back on with the same code. ARRRHHHHHGGGG...

    so new EGR and EGR gas temp sensor, only part left is the VSV, and the ECM. looks like the VSV is 50.00.

    Has anyone changed the VSV before, how big of a job is it> Also, anyone have any other ideas of what could be causing this code?
     
  7. 98tacoma27

    98tacoma27 :POOPCORN: Staff Member

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  8. ao6902

    ao6902 Well-Known Member

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    is the code for insufficient flow? Don't know why I didn't think of this before but first thing I do when I see egr code is pull valve off and start the car. Car should run extremely bad and just about die with egr off (basically you are creating a huge vacuum leak). If car runs fine or only changes a little with egr off, then the egr passage in the intake manifold is blocked up and needs to be cleaned. If you haven't done so, check that before you buy any more sensors
     
  9. vapovick

    vapovick [OP] Active Member

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    The 401 is for insufficient flow, the 402 is for excessive flow.. Its driving me crazy. I don't want to have to take this in, but i'm 400.00 deep now.

    I am gonna try and pull the EGR VSV and test it first.

    If anyone has any other ideas, let me know. thanks for all the responses.

    ./vv
     
  10. ao6902

    ao6902 Well-Known Member

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    Yea that would make more sense. If you had a restriction in the intake port it would kick up an insufficient flow code. Good luck
     
  11. Toyota Tech31

    Toyota Tech31 Sometimes when I close my eyes, I can't see.

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    I would personally be replacing the VSV, very common with EGR system that they go bad.

    DTC No.. DTC Detecting Condition Trouble Area

    P0402

    EGR gas temp. sensor value is high during EGR cut

    off when

    engine is cold and vacuum is applied to port E.

    (2 trip detection logic)


    EGR valve stuck open

    EGR VSV open malfunction

    Open in VSV circuit for EGR





    Short in EGR gas temp. sensor circuit

    EGR valve is always open (2 trip detection logic) ECM


     
  12. vapovick

    vapovick [OP] Active Member

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    Ok, looks like I found the part. Anyone replace this before?


    There is a nut on the right side, maybe 15m. which looks like a real pain.

    or there is a single screw and tab, accessiable from the inside of the intake manifold (looks simple, just unscrew it and swap it out, much easier than the nut.


    So anyone with exp care to comment? The part is 54.00 at the auto store, and 87.40 OEM...

    Should I go OEM, or OE from Dorman?

    Thanks again..
     
  13. vapovick

    vapovick [OP] Active Member

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    OK, went OEM. Monday I'm planning on replacing the EGR VSV and the EGR modulator... I will update soon....
     
  14. vapovick

    vapovick [OP] Active Member

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    OK, I have both parts replaced, the vsv and the EGR modulator. Very very simple. The CEL is off and has been for 60+ miles, about 15 stop starts.

    Crossing fingers that I have corrected the issue.

    Back story:
    I had an exhaust manifold crack, a very large on at that. I replaced the manifold, only to shortly thereafter blow both O2 sensors. Most likely the result of cold air being pulled over the sensor when it was hot. I think this may have also slowly caused issues with the EGR system. With such a generic code 0402 Excessive flow, I swapped the EGR Valve and the CEL returned 1 week later. Getting a strange reading on my multi tester, I then replaced the EGR gas temp sensor. Week later, CEL again. So I go OEM EGR Modulator and VSV for the EGR, both now swapped out.


    So, with the theory of deduction haha.. I have really replaced it all, minus the ECM...

    Took the VSV inside and hooked a battery up to it, nothing, no clicks... So what does everyone think? That the VSV was stuck open? Shouldn't I hear some clicks if I hook up a 12 power supply to it? (the VSV) I also put a vacuum pump on both ports from the VSV and was able to pull vacuum.

    So this is all really strange, I am just hoping I have got this under wraps!


    Thanks for any and all input.


    ./vv
     
  15. ao6902

    ao6902 Well-Known Member

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    I wouldn't over think it bro. Most likely you've got the problem solved especially since you've driven 60 miles and no light. In my experience with many different types of cars, egr monitors are one of the first to set meaning that once you've cleared the light the computer tests each system to see if in fact everything is ok. For the oxygen sensor and egr systems, this usually happens within the first 10-15 miles of driving after clearing the cel. Catalytic converter, evaporative and secondary air (if so equiped) are usually the last to set. Sooooo, if it was me, I'd roll on with my mind at rest....until something else pops up :)
     
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