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Thread: Golf Mk5 1.9 TDI Amber ECU light stays on with new EGR valve

  1. #1
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    Golf Mk5 1.9 TDI Amber ECU light stays on with new EGR valve

    Car is 2007 Golf 1.9 TDI Automatic, Engine Code BXE


    Problem is : Amber ECU light, if cleared by resetting, comes back on , when next started.

    VCDS reports "Motor for Intake Manifold Flap (V157): Malfunction"


    and cheap from ebay Elm bluetooth connecter with Torque mobile app reports two errors -
    1) P2100 Throttle Motor Circuit open
    2) P2102 Throttle Motor circuit low.

    Motor intake flap is the EGR valve, confusingly also called Throttle Body, or ASV (Anti Shudder valve).

    The EGR valve is new 200 quid jobbie !!!


    And of course I cant get the car through MOT with this problem, which is soon, so hyper annoying !!!


    History:
    Driving on motorway, amber ecu came on (before this car was a bit lumpy driving uphill on motorway).
    AA did a scan and said I needed a new Throttle body.
    I changed throttle body myself, A pierberg sourced from Murrays Direct near London.
    Car now drives alot better (good).
    Amber ECU light STILL on, after a reset from Elm or VCDS.
    After resetting Amber ECU, the light never comes back on when driving for that session (good).
    When next restarting engine, Amber ECU light comes on.


    The errors stored are consistently as listed above. So there must be a problem somewhere in the electrics !


    I've read fuse 8 or 24 can be blown, checked them and they are ok.




    Some underbonnet tests I did yesterday:


    Took off intake hose, i could see the flap is in open position. I guess thats why the car still runs.
    I did some testing yesterday with a multimeter, and found of the 4 pin connector that only 3.22 volts
    is being read into it. Other 3 pins 0, this may be normal.
    When i test I (think) the coolant sensor nearby , it has 4.95v feed in (normal i think).


    So it seems the voltage going to the EGR connector is not high enough.


    Not sure if any relays can be checked or are used or where/what to try next without giving car over
    to maybe mega expensive dealership.




    If someone cracks this, free beer will be posted, driving me nuts !

  2. #2
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    V157/anti-shudder/TB and EGR valve are distinct separable things, items 3 & 1 here, respectively: https://volkswagen.7zap.com/en/rdw/g.../1/131-131060/

    Your description above seems a bit confused on this. For example "Motor intake flap is the EGR valve"... No, it isn't.

    Anyway, this sounds electrical, so I may be able to help. On a BXE engine in a friend's Touran the wiring to V157 cuts across forwards in a way that looks as if could be easily strained or abraded when work is done in that area; so I'd start with a close look at that if I were you, looking for insulation or wire damage, including/especially just where it exits the connector plug.



    I'll have a look at wiring info shortly. Can you confirm that you have the following wire colours going to V157?
    Pin 1 Brown (2 separate wires shown on diagram?)
    Pin 2 Blue/red
    Pin 3 Violet/grey
    Pin 4 Violet/yellow
    Last edited by Pete1; 03-03-19 at 13:32.
    My car: 2003 Polo 1.4 BBY, Petrol
    Good Lady's: 2005 Mk1 Skoda Fabia 1.2, AZQ

  3. #3
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    Can you also confirm which fuseholder you checked the numbers 8 and 24 in, under dash or under bonnet?
    My car: 2003 Polo 1.4 BBY, Petrol
    Good Lady's: 2005 Mk1 Skoda Fabia 1.2, AZQ

  4. #4
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    Thanks Pete, good to be clear. I've changed the throttle body valve, part no on ebay 03g128063cv140, looks like No.3 in your diagram.
    l

    Click image for larger version. 

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    My friend has the VCDS software , i think he was checking this page

    Yes the wiring runs across the top of the engine, I've tried checking and moving it with the multimeter attached and the voltage stays constant at 3.22 V.

    Yes those are my wiring colours for the connector attaching to it.

  5. #5
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    Under bonnet fuses. The bigger ampage ones. All seem ok.

    Yes those are my connector wiring colours. Have replied earlier with a pic of the part I've changed (modorater needs to check it), throttle body is clearer description about the changed part.

  6. #6
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    OK, good. So next step is to check continuity of power and earth wires.

    12V feed wire from fuse 24 to pin 2 in the connector, blue/red wire (don't worry about checking for voltage, that comes from the relay next to the fuse, and I'm not sure exactly when that will be on, definitely when engine running, but not sure about ignition only). If you have continuity, you'll have voltage when there should be.

    Earth on pin 1 to engine or chassis metalwork, or battery negative.
    My car: 2003 Polo 1.4 BBY, Petrol
    Good Lady's: 2005 Mk1 Skoda Fabia 1.2, AZQ

  7. #7
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    To confirm, to check power continuity, find some testing spare wire and connect to one side of fuse 24 and other to pin2 of wiring connector, and check for zero resistance ?

    To check earth continuity for pin1, use multimeter probes between pin1 and anywhere normally earthed.

    sorry to sound a bit of an idiot.

  8. #8
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    If your multimeter leads will reach, just put one probe on one end of fuse 24, the other to pin 2 of the V157 socket (unplugged from TB). If not, extend one of the probe leads with wire as you suggest.

    Yes, in both cases, looking for zero Ohms between the mentioned points.
    My car: 2003 Polo 1.4 BBY, Petrol
    Good Lady's: 2005 Mk1 Skoda Fabia 1.2, AZQ

  9. #9
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    Do these checks with ignition off, keys in your pocket, to be safer against accidentally shorting 12V through your meter.
    My car: 2003 Polo 1.4 BBY, Petrol
    Good Lady's: 2005 Mk1 Skoda Fabia 1.2, AZQ

  10. #10
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    If those both check out OK, test the other two wires in the same way, pin 3 to ECU pin 60 of a 60-way connector, pin 4 to pin 25 of the same 60 way connector.
    Probably best to disconnect battery negative before unplugging ECU connector.
    Last edited by Pete1; 03-03-19 at 14:53. Reason: 26 corrected to 25
    My car: 2003 Polo 1.4 BBY, Petrol
    Good Lady's: 2005 Mk1 Skoda Fabia 1.2, AZQ

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