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S4 EGT Sensor

Discussion in 'A4/S4 forum(B5 Chassis)' started by aragorn, Oct 19, 2009.

  1. aragorn

    aragorn "Stick a V8 in it!"
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    So i've got this fault code:

    17866 - Exhaust Gas Temp Sensor 2 (G236): Short to Ground

    Any idea which bank this is on?

    I know one is "easy" to change, and the other one is a pig... Looking at the engine, the "offside" bank looks to be quite easy to access, whereas on the nearside i cant even see the sensor!

    Cheers.
     
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  3. PW-Motorsport

    PW-Motorsport Member

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    Bank one is the left side
    Bank two is the right side

    Bank one is the pain, it is located on the underside of the turbo/downpipe, you can get at it from the under the car. There is a small gap between the drive shaft and the subframe to get you hand in with an adapted ring spanner to remove it. Needless to say wait for the engine to cool !!

    Hope this helps.....
     
  4. aragorn

    aragorn "Stick a V8 in it!"
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    Ahha! So the faulty one is the easy one then! Thats one bonus anyway.

    I've reset the code. Will see if it comes back or not and then look at ordering a replacement if it does.

    Are these sensors known to fail by themselves, or is it some other faulty component that causes them to fail?
     
  5. PW-Motorsport

    PW-Motorsport Member

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    The EGT`s can be helped on their way by faulty mafs.

    They can also be damaged by the exhaust manifold failing. The double skin manifolds can fracture/welds fail and the loose part can damage the EGT.
     
  6. aragorn

    aragorn "Stick a V8 in it!"
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    I presume if its damage from the manifold i will see it when i remove it?

    Not sure if the MAF is faulty or not. The enignes never quite been 100%. Theres no boost leaks, however on a full throttle 3rd gear pull it was cutting throttle drive back to 50% (only noticeable on vagcom, the car drives normally) and the peak g/s was indicating about 255-260hp, ie a bit short of normal. Cant really find any explanation for this low figure though...

    Cheers
     
  7. aragorn

    aragorn "Stick a V8 in it!"
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    Had a little test drive earlier to see if we could get it to pop the EGT code again.

    Didnt seem to but i managed to get a log of the odd throttle cut:
    [​IMG]

    Thats only 2nd and some of third, theres not really enough road round here to do any more quickly.

    As you can see, throttle starts off at 100%, then drops back, reaching ~75-80ish in this case.

    For some reason this S4 ECU doesnt register spec'd boost against actual on channel 115, but looking at the actual value on channel 118, it seems it spikes to around 0.65bar when the throttle was first put down, then drops back and holds around 0.5-0.55bar, which doesnt seem particulary excessive?
     
  8. jonnya

    jonnya Member

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    You might want to check the fueling. I know you get overfueling with a bad EGT,
    perhaps you get throttle cut as well?
     
  9. aragorn

    aragorn "Stick a V8 in it!"
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    Ye, this EGT fault is relatively new though, its had the throttle cut since he baught the car last year.

    It doesnt fault code (well does now obviously but didnt before) and drives completely normally, the cuts only visible when viewing the logs on vagcom, and you cant even feel it.
     
  10. PW-Motorsport

    PW-Motorsport Member

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    Look as pending codes as well......

    Fault codes are only stored if the error lasts for, I think around 30 secs.
     
  11. aragorn

    aragorn "Stick a V8 in it!"
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    Pending codes? How do i look at those?
     

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