Help me to solve code of P0401

Discussion in 'VW Mk4 Jetta, Golf, New Beetle, Passat TDI forum' started by 91NCTDI, Feb 24, 2012.

  1. 91NCTDI

    91NCTDI New Member

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    Car:
    2003 Jetta TDI
    I can't find a solution to this problem.
    Today, I took a black n18 valve (which the tab isn't white) out of a Beetle (tdi) to replace the one I have in my 2003 Jetta (tdi) with a code of P0401 because I wanted to see if it would solve the problem but unfortunately, it didn't. Therefore, I have the EGR and the intake manifold cleaned out. So what should I do?
    *
    Should be n239 valve bad?
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  2. Keithuk

    Keithuk Super Moderator

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  3. jgeorge

    jgeorge Member

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    Does the sudder valve function properly? You should hear it right after you shut the engine off- Closes then re-opens. You may need someone to turn off the car while you watch. Its part of the egr valve.I had code 401, replaced the egr, problem solved. 03 golf.
  4. 91NCTDI

    91NCTDI New Member

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    We took egr valve test with air pressure and it work fine as vw shop say. So they said n239 not control egr valve right? Also it get no air out n239. Yes, we test when we start engine and see if it move and it didn't.
  5. jgeorge

    jgeorge Member

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    The shutter valve operates when the engine is shut off, not when its started.- You are saying you dont see it move at all right? If you dont see the valve lever swing momentarily to the closed position, then reopen, chech for vacuum to the valve.- Vacuum will only be supplied momentarily when the engine is shut off, so you need someone to turn off the engine while you check. If thers no momentary vacuum then the problem is upstream from the shutter valve. To test the egr valve itself to see if its seized, remove the intake pipe at the valve, use a hand vacuum pump and apply vacuum and watch the egr valve stem for movement. No movement then its seized. If it opens sufficiantly then the problem is upstream from the egr valve.
    Last edited by a moderator: Feb 25, 2012
  6. Frank M

    Frank M Member

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    Attach a vacuum gauge to the vacuum line coming from the N18 where it attaches to the EGR nipple. If you get vacuum on and off, (may have to goose the pedal and watch it), then everything controlling the EGR is ok.

    Attach mity vac to EGR nipple and listen for engine noise changing at idle. If you get a change them problem is not EGR or plugged EGR cooler/circuit. If no change then manually open the EGR with a needle nose and listen for a change. I you get a change then the EGR diaphragm is bad. No noise is plugged exhaust through EGR cooler.

    I am assuming you have no mods for this line of diagnosis.

    Or you can monitor MAF readings and EGR with VAG if you have one.
  7. 91NCTDI

    91NCTDI New Member

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    I look up vag-com that maf reading show 485 to 515mg so I order brand new and I look at part number and found it was wrong part that installed on my car. The part came off my car that show 06a 906 461 which that came out 1.8t jetta and tdi maf part should be 036 906 461c and I hope it will make check engine light off.
  8. rmchambers

    rmchambers New Member

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    I have this code all the time from having my EGR diaphragm hose unhooked and plugged to as to avoid re-sooting up my intake. when I go for emissions I put the hose back on and clear the code until it is ready then once it passes plug the hose again. My scanguage II shows better MPG when the EGR is disabled. I don't really want to have to clean that intake again either.
  9. Bryant

    Bryant New Member

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    I used to have the same problem, but I clear the fault code with my v-check a302, and now it is all right.
  10. 91NCTDI

    91NCTDI New Member

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    So far I have replace or clean out is
    Egr valve clean out (there is 2 of egr valve and I replaced both and still get MIL)
    Intake manifold clean out
    Egr cooler pipe clean out
    Egr filter clean out
    Anti shutter valve good
    Brand new borsh maf
    One new vaccum line for turbo vnt actuator.

    I still have same code of P0401. This is so silly to waste my time. I have state inspection due before april 15. It any other idea I can solve it?
  11. 91NCTDI

    91NCTDI New Member

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    Once you clear code and drive about next 20 to 50 miles and check engine light come back on.
  12. Keithuk

    Keithuk Super Moderator

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    Thats sounds about right as clearing the codes does just that but unless you fix the problem at the source it will come back.
  13. 91NCTDI

    91NCTDI New Member

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    I clear the code for every part and it keep check engine light come back on.
  14. sonxbuy

    sonxbuy New Member

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    Attach a vacuum gauge to the vacuum line coming from the N18 where it attaches to the EGR nipple. If you get vacuum on and off, (may have to goose the pedal and watch it), then everything controlling the EGR is ok.

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