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2.5TDI BDG Engine Speed signal

Discussion in 'A4/A4 cabriolet/S4 forum(B6 chassis)' started by JasonS, Jun 18, 2013.

  1. JasonS
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    JasonS Member

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    [Jun 18, 2013]
    I just had my brake fluid changed by my local Indy..

    On the way home I tried some spirited braking, just to be sure.. Then my engine light came on and the glow plug light is flashing.

    VCDS scan reveals:

    01126 Engine Speed Signal
    03-10 No signal - Intermittent

    I've checked all the engine measuring blocks, all are within spec, the fuel pump checks out and is getting power.

    I checked my workshop manual and can't find the G28 sender where it's supposed to be, under the coolant expansion tank.

    Where should I be looking?
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  3. hodgy0_2
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    hodgy0_2 Member

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    [Jun 19, 2013]
    i believe the g28 sender is attached to one of the injectors (underneath the drivers side cam cover)
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  4. JasonS
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    JasonS Member

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    [Jun 19, 2013]
    I think that's the needle lift sensor..

    I've ordered a speed sensor and will be getting under the car later tonight. I think it's at the rear of the block on the passenger side, in line with the crank.
    I'll see what I can find.
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  5. hodgy0_2
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    hodgy0_2 Member

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    [Jun 19, 2013]
    Yes, you are correct, the needle lift sensor, but I believe it is the drivers side on a 2.5tdi

    mine has never worked since I had had my car, does not seem to cause an issue
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  6. JasonS
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    JasonS Member

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    [Jun 19, 2013]
    I've fixed it (for now)..

    I went out to go looking for the speed sensor, and figured out that its attached to the grey plug mounted on the bulkhead..
    ImageUploadedByTapatalk1371672049.722296.jpg
    I loosened the cable a bit and cleaned the contacts with some DeoxIT from my tiny tube.

    After that I cleared the codes and left it for a few minutes, usually the fault would come back in a few seconds, but not this time..
    So hopefully it was just a wiring fault.

    I've been out and replicated my braking, just to be sure, and it's still clear.

    I'm going to pick up a speed sensor anyhow, just in case it doesn't last.
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  7. hodgy0_2
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    [Jun 19, 2013]
    Nice onE

    i might try the wiggle technique tomorrow
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  8. JasonS
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    JasonS Member

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    [Jun 20, 2013]
    It's gone again.. I drove 50 miles to work with no trouble, then 15 miles into the return, the lights came on again.

    I'll pickup and hopefully fit the replacement at the weekend.
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  9. hodgy0_2
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    hodgy0_2 Member

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    [Jun 21, 2013]
    Let me know how you get on jason

    also does a failure of this sensor cause an engine light to illuminate, if so I think the person I bought my car off has disabled the light, which is a bit naughty
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  10. JasonS
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    JasonS Member

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    [Jun 21, 2013]
    Yes, when you turn on the ignition, you should see two amber warning lights on the dash
    An 'engine' light on the top left, a 'glow plug' light on the lower right.

    These should both go out once the engine is running. - if no fault codes are present.

    At the moment, my engine light stays illuminated and the glow plug light flashes to warn me.
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  11. JasonS
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    JasonS Member

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    [Jun 24, 2013]
    ARRGH!

    I replaced the engine speed sender, which was a rotten job, very fiddly and very difficult to get my hand and tools into the right place..

    Only to find that the fault is still present.

    So I turned my attention to the socket and wiring from the sender plug to the ECU, I found that if I twisted the wiring slightly, the fault goes away, so it looks like the wire has got hot and gone brittle over the years, so I'll probably have to get hold of some repair wires and splice into the loom to prevent further problems.

    Bah. 40 quid and two hours for nothing.
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  12. JasonS
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    JasonS Member

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    [Jun 30, 2013]
    All sorted..

    Water in the ECU sockets..
    How it got there I have no idea, no signs of ingress..

    ImageUploadedByTapatalk1372608935.169277.jpg
    ImageUploadedByTapatalk1372608963.285849.jpg

    Cleaned with WD-40, dried, then cleared codes.. Seems to be running OK now.
    #11

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