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EGT Sensor implausible signal fault.

Discussion in 'A3/S3 Forum (8L Chassis)' started by sean_s3, Dec 15, 2009.

  1. sean_s3
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    sean_s3 Member

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    Hello everyone.

    17868 Exhaust gas temp sensor 1 (G235) Implausible signal . P1455 - 35 - 10 Intermittent.

    The fault code for the exhaust gas temp sensor keeps appearing every so often. After doing a bit of research and seeing how much these things are i would like to leave it a while before i get it sorted. Im just wondering if doing this could do any damage ?? The car drives fine so until there is a noticeable difference im not in no rush to sort it unless its necessary.

    Any help would be greatly appreciated.
    Thanks Sean.
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  2. S3 Paul
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    S3 Paul Moderator Moderator

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    mine had this problem ages ago... i changed it straight away as it ment the ecu couldnt keep tabs on just how hot the turbo, manifold was getting and back things off if it needs to.
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  3. sean_s3
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    sean_s3 Member

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    Ok it sounds like its an important sensor then so its probably best to get it changed. The car has started over-boosting from 3000 to 4000 rpm and since this is the only registered fault vagcom can find i think the EGT sensor is to blame.
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  4. S3 Paul
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    S3 Paul Moderator Moderator

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    Im not sure it will course the over boost problems... i would maybe check all the vacume hoses to and around the N75 valve .
    Im not sure if the ecu goes into soft limp mode when it registers the EGT sensor fault,
    When the car is cold... have a little check that the sensor isnt loose. this can happen and make for funny readings both boost and egt's
    Be careful when you remove it at the nut comes undone quite easy... but then the sonsor its self can be stuck quite tightly into the turbo housing. probably down heat... cold... heat... cold of everyday use and the odd bit of exhaust sut too,
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  5. sean_s3
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    sean_s3 Member

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    From what ive read the EGT fault will cause the ecu to limit boost rather than add more so maybe the N75 or another boost controller is at fault. However when i clear the fault there is no surging . Where exactly is the sensor located ?
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  6. S3 Paul
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    S3 Paul Moderator Moderator

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    Which sensor do you mean?
    The EGT sensor ( on my car any way face lift 2001 amk ) is located in the exhaust housing of the turbo on the right hand side... the wire from it then goes around the engine on the gearbox side and under the inlet manifold. if you remove the trim around the dipstick you will see where it plugs into the loom of the car.
    The N75 valve sits ontop of the turbo intake pipe, Just about level with the strutbrace again on the right handside of the engine.
    The N2... valve sits onto of the engine to the front of the rocker cover.
    Hope that either makes sence or atleast points you in the right direction
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  7. sean_s3
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    sean_s3 Member

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    Yes the EGT valve, i read its quite awkward to get to as it behind the exhaust. Ive had a brief look and i cant see anything wrong around the N75 or N249. The overboosting at 3k is intermittant and doesnt always happen, sometimes its fine. Its booked in on tuesday at a local VAG garage who hopefully will be able to sort it.
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  8. sean_s3
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    sean_s3 Member

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    The car has been in for inspection today and i will be getting a new EGT sensor, serpentine belt and tensioners and a rear ARB and bushes fitted in the new year. Unfortunatly the overboosting issue is actually the sign of a slipping clutch. 75K and a recent remap have seen it off so this will be getting replaced as well. Its going to be an expensive bit of work so i want to stick with the OEM clutch and flywheel if possible.

    Whats the opinion on using the standard clutch with a stage 1 remap ?
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  9. sean_s3
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    sean_s3 Member

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    Any thoughts on this people ?

    The garage who did the inspection have quoted me £1224 including VAT @ 17.5% to do the clutch. This includes the clutch assembly , dual mass flywheel , new clutch release bearing and a full 4 wheel alignment. All the parts are sourced direct from Audi hence the price .

    Any help would be very much appreciated.
    Thanks.
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  10. S3 Paul
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    S3 Paul Moderator Moderator

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    I fitted and ran a standard Sach clutch on a LUK new flywheel and release bearing.
    Think it came in at 540 for the parts back when i was running stage 2 software. I was told "dont stick your foot in the floor at low revs and make the boost do the work" as this kind of driving will put the clutch under a lot of strain
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  11. sean_s3
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    sean_s3 Member

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    Yes true. I always try to feed the power in gradually but i think it was the previous owner who will have contributed to the damage , the remap has just speeded up the inevitable. Looking at previous posts my quote seems above what most people have claimed and the price for the parts is almost £200 over what you paid so im gonna get a few quotes from other places.

    How much torque did you have from the stage 2 ? I think on a basic stage 1 i should be ok with another standard clutch.
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  12. S3 Paul
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    S3 Paul Moderator Moderator

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    erm i cant remember off hand what the torque was but i did run the same standard clutch on my hybrid turbo for almost a year . When i took the engine out to rebuild it i could see the clutch had not been happy. it was blue and the flywheel was too. Feed it in steady with no riding of the clutch... you will be fine. Oh and steer clear of "launching" as this will only speed up how quickly you need the next clutch
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  13. S3Lol
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    S3Lol Member

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    I have the same issue with this fault code and revs surging Sean. Fitting TB Blueflame over the coming weeks so will probably be easier for me to do it while that is off.
    Last edited: Jan 11, 2010
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