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Water in ECU Box

Discussion in 'A4/A4 cabriolet/S4 forum(B6 chassis)' started by Dibs_h, Sep 16, 2011.

  1. Dibs_h

    Dibs_h New Member

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    I have a 53 plate 130 TDI Avant. Previously I've had the main fans still running with the ignition off - temp fix was to pull the fuse, and after reading up on here, opening up the ECU box, after having cracked the bloody screen getting the drivers side wiper arm off - only to find almost an inch of water in there!

    Removed water, dried out the relays (replacing 1 of them) and no issues going forward. This was about a year ago.

    A few nights ago - leaving a car park and got that "bang" noise\feeling as if the car had stalled, but the clutch wasn't down - looked at the dash and the revs had picked up again, ESP light was lit on the dash and it wouldn't go past 2k revs. The Engine light would come on.

    Pulled over (luckily it was local) - switched off the car and back on again, and there was a weird noise coming from the engine bay. Later on found out it was the ABS pump - doing a on\off routine [realised it was this when I plugged VCDS in and had it test the ABS, with no errors reported]. Switched it off and on again - same noise. Thought what the hell and started it and it rev'd over 2k with no issues.

    Got home and plugged VCDS in and it came up with the following,

    Monday,12,September,2011,23:34:47:46626
    VCDS Version: Release 10.6.4

    Address 03: ABS Brakes Labels: 8E0-614-517.lbl
    Control Module Part Number: 8E0 614 517
    Component and/or Version: ABS/ESP front 3429
    Software Coding: 04255
    Work Shop Code: WSC 06435
    VCID: E5CBCE9E55F1
    1 Fault Found:

    18258 - Powertrain Data Bus: Missing Message from ECU
    P1850 - 35-10 - - - Intermittent

    Reset the code and no issues the following day. The more I thought about it, the more I felt that the car had actually cut out momentarily , hence the "bang" as if it had stalled. With the car "switching" back on and in motion, it had effectively bump started itself - so how had it cut off. When I had the ECU box open last time - I'd realised one of the relays was powering the ECU.

    So popped the box open again - lo and behold, water in the bottom and relays soaked. Dried it all out again and no further issues.

    But - it's annoyed the hell out of me over the last day or 2 - so a bit more searching brought up the drain bungs\grommets. So rung up Audi UK & based on the chassis nbr - the recall is not applicable, so I was told. Anyways - yesterday evening had a look at the bottom of the battery and there was no more than 1/4 inch of water there, couldn't see that making it's way into the ECU box.

    Removed the batter side bung completely - even though it was emptying out freely, as is the servo side one (get this removed over the weekend)

    Anyone have any thoughts as to how on earth water is getting into the ECU box? It's not cracked, the seal is intact.

    Cheers

    Dibs
     
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  3. mememe

    mememe Member

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    Build up of water in the plenum chamber is the most likely cause. Dont delay, get the grommet out asap. Could be very expensive for you if you dont.
     
  4. Dibs_h

    Dibs_h New Member

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    Thanks for that. I used a SnakeCam to check and to say both grommets were draining freely is an understatement. No silt, blockages of any kind. The design of the grommet was such that blocking would be difficult. I can post a picture of the one I removed if it helps.

    The servo one is still there - will remove on Sat. It would require something like over 4 inches of water to even get to the ECU box or say 2 inches and a sharp left turn for the water to go that high. There is physically no way that much water could build up - given how freely the water was flowing out of the grommets.
     
  5. hades-

    hades- Yorkshire & Humber Rep.
    Regional Rep VCDS Map User

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    there was no more than 1/4 inch of water there

    if it was flowing out that freeley then you wouldnt have any water in there at all
     
  6. Dibs_h

    Dibs_h New Member

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    I see what you mean - I just put it down to perhaps the metal not exactly being shaped like sink and some residual water would always sit there.

    Do you think that even with so "little" water in the bottom, a bit of hard driving could force the water up the side and perhaps into the ECU box?

    Thanks.
     
  7. hades-

    hades- Yorkshire & Humber Rep.
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    iv no idea how it gets in the box but as you know it does
    last 1 i did i changed the seal on the box and all was fine
     
  8. Dibs_h

    Dibs_h New Member

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    Thanks for that. I'll get the remaining grommet out this weekend and get a seal next time I'm placing an order with TPS.
     

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