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Thermostat or Temp Sensor?

Discussion in 'A3/S3 Forum (8L Chassis)' started by danger S3, Nov 13, 2012.

  1. danger S3
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    danger S3 Member

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    [Nov 13, 2012]
    Hi,

    i know this has been covered alot but I'm just curious about something.
    My mates got an A3 8L and the temperature wasn't reaching 90C when driving on motorways or A roads but driving round town it does get up there.
    I scanned the car with VCDS and there was the fault:

    17704 - Error in Mapped Cooling System (check Temp-Sensor and Thermostat)
    P1296 - 35-10 - - Intermittent

    I advised him that it was the thermostat (as i had the same thing with my S3 and i replaced the thermostat and it was all fine after that) and he got the garage to replace it but its still not reaching temperature.

    question is surely that's a sign its still the thermostat at fault as if it was the temp sensor that was faulty it wouldn't reach 90 at all?

    cheers for your wisdom

    Ali
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  3. IGI
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    IGI Member

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    [Nov 13, 2012]
    If you have vcds you can check temp value for engine ecu 01 and check temp value for dash ecu 17 as temp sensor feeds both seperately value should be the same if not replace temp sensor
    Does sound odd i would also have said thermostat if at 90 in town and then drops down out of town
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  4. danger S3
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    danger S3 Member

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    [Nov 13, 2012]
    just went for a run while measuring the temps and the temps all seem to match up.

    it was taking ages to get up to temperature so i stopped and idled and it went upto 90C, after that i went for a drive along the bypass and fairly quickly it dropped down to 75C. then when i was in traffic or stationary it started to go back up.

    He's reluctant to take it back to the garage to get them to look at it and change it again in case its not the thermostat.
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  5. IGI
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    [Nov 13, 2012]
    Does sound like thermostat fault to be fair like its stuck open.....cheap thermostat?
    If its been done at a garage should get him to take it back they should look at it free of charge if they supplied the part:thumbsup:
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  6. danger S3
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    danger S3 Member

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    [Nov 13, 2012]
    i Just spoke to the garage and it was a part from TPS that went in it so its genuine and he was saying if it does turn out to be a faulty thermostat then they will replace it but if its not then there would be a charge which is perfectly reasonable, especially as initially it went in to get the thermostat replaced not to find out why it wasn't sitting at temp.

    he was saying it might be the temp sensor on the engine (i think its the white one, the green ones in the pipe which is just for the gauge. i could be wrong on that though) that's not working properly.

    going to try and persuade my mate to take it back to them and ask them to look into why its not sitting at temperature. they're a good garage and my family an friends have used them for years so we trust them (even though we do most of the work ourselves).
    seems like the most sensible plan i think.
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  7. 16Klappe
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    16Klappe Princess Clap.

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    [Nov 13, 2012]
    Those symptoms are the thermostat. :)

    I did one myself in the road outside my house the other day, had nothing by a 10mm spanner. Took about and hour and cost a fiver in parts.

    I put at least £34 in my swear jar though.
    #6
    Lavis89, Tim_Attard and Birdy like this.
  8. BENJAMIN
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    BENJAMIN Active Member

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    [Nov 13, 2012]
    100% thermostat issue....
    #7
  9. danger S3
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    danger S3 Member

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    [Nov 13, 2012]
    yeah, i had the same symptoms on my S3 and changed the thermostat and that sorted it but he's not willing todo something like that himself and would prefer the garage todo it. fair enough really.
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  10. IGI
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    [Nov 13, 2012]
    Fair enough on the garage id say since they were only asked to change thermostat,probs only ran round block to check up to temp ....would doubt on a genuine part being faulty but you never know
    What age / engine is the A3 ?
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  11. danger S3
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    danger S3 Member

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    [Nov 13, 2012]
    tha A3 is a 52 plate and its done about 75k.
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  12. IGI
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    [Nov 13, 2012]
    Engine ?
    Still cant see it being anything other than the thermostat as it shouldnt cool down on road. Normally when temp sensor goes wrong it reads wrongly all the time and if totally buggered fault code flagged.Have changed loads of temp sensors over the years
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  13. 16Klappe
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    16Klappe Princess Clap.

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    [Nov 13, 2012]
    2002 will be an AUM.

    It'll be the thermostat, just get on with it ;)
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  14. danger S3
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    danger S3 Member

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    [Nov 13, 2012]
    hahaha, aye its an AUM.
    The garage also checked it was the correct temp of thermostat that went in it and it was the 88C one which is correct, rather than like a 75C one.

    my mates away down south in his car for a week so it won't be getting sorted till he gets back but i will report what the outcome is when he eventually takes it back to the garage.

    my moneys on the thermostat as well :sly:
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  15. IGI
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    [Nov 13, 2012]
    sweepstake:yes:
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  16. 16Klappe
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    16Klappe Princess Clap.

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    [Nov 13, 2012]
    Petrol VAG thermostats open at 87*, not 88.

    x
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  17. danger S3
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    danger S3 Member

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    [Nov 13, 2012]
    Sorry Klappe. 87C :thumbsup:
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  18. Welly
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    Welly VX220 SC Driver :)

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    [Nov 14, 2012]
    Yep, it just is the thermostat. Temp sender is working because you're seeing the temp rise. It really is just that simple.
    #17
  19. BRG_GTI
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    [Nov 14, 2012]
    Sorry to hijack the thread but I am having the same issues with a 2001 AMK engine. Can anybody tell me a part no from Audi or TPS ?
    #18
  20. danger S3
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    danger S3 Member

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    [Nov 14, 2012]
    I got mine back in Feb for my 2001 S3 AMK

    The part number was 050 121 113 C and it was about £23 and if i remember correctly it came with a new seal. worked perfectly.
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  21. BRG_GTI
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    BRG_GTI New Member

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    [Nov 14, 2012]
    Nice one thanks. Was that from audi or TPS ?

    If its from TPS do they send items as the nearest TPS is about a 2hr round trip and a bridge crossing ?
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  22. danger S3
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    danger S3 Member

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    [Nov 14, 2012]
    i got mine from Audi, i think TPS only deliver to garages so it would goto the nearest one. could be wrong though (wouldnt be the first time)
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  23. 16Klappe
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    16Klappe Princess Clap.

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    [Nov 14, 2012]
    TPS do only deliver to trade, personally I would just get the cheapest thermostat from the nearest auto factors. Chances are it is the same unit anyway, and what with them needing doing every 3 years anyway personally I don't see the point in buying a £25 thermostat.

    Mine was less than a fiver from GSF.
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  24. BRG_GTI
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    [Nov 14, 2012]
    I spoke to local audi and it was £ 26.00 incl vat couple of days delivery time. ill see what the local motor factors are was it a "main brand" of thermastat ? just I thought I read somewhere that the cheap ones were not as long lasting ???

    Just a separate thought is it worth starting a sticky with audi part nos and descriptions or has this been covered ?
    #23
  25. danger S3
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    danger S3 Member

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    [Jan 30, 2013]
    ok solution time.
    so to recap my mates car wasn't reaching temp unless idling, i advised him it was the thermostat so he got the garage to replace the thermostat, the problem still remained.
    like everyone else on here i said it was still the thermostat but just to please him we changed the temp sensor.... problem still remained.
    so he eventually put the car back in for the thermostat to get changed again and hey presto the car now reaches temp and runs normally.
    cheers everyone

    Ali
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  26. Birdy
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    Birdy Member

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    [Jan 30, 2013]
    Just had the same fault.apy 2000 stat replaced, sorted it
    #25
  27. 16Klappe
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    16Klappe Princess Clap.

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    [Jan 30, 2013]
    Ching ching ching.

    Where's my prize money?

    -

    Glad it's all sorted; problem finding is just a case of collecting the symptoms and identifying which fault could cause all of them at once. Thermostats are a nice and easy diagnosis :)
    #26
  28. mazzaman
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    mazzaman New Member

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    [Jan 30, 2013]
    hi guys well my a3 doesn't move of 60 at all so would you suggest changing both sensor and stat?

    should this eliminate the problem
    #27
  29. mazzaman
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    mazzaman New Member

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    [Jan 30, 2013]
    Also does anyone know any guides to follow to fit stat and sensor
    #28
  30. danger S3
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    danger S3 Member

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    [Jan 30, 2013]
    if does it not even leave 60C when its sitting idling for ages?
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  31. mazzaman
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    [Jan 30, 2013]
    i was in stop start traffic for 35 mins today and it went over the 60 line a smidge then went back.

    Is this going to cause head probs if i dont get it sorted asap and you know and guides to fit it please.
    #30
  32. Spatula
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    Spatula 1.8T AGU

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    [Jan 31, 2013]
    I am also suffering from this problem at the moment. I recently (yesterday) had my timing belt and water pump changed. When I went to pick it up the garage had had my car sat idling for 20 minutes before I arrived to make sure the water pump was working OK. When I got in the car the temp was at 90, but as soon as I started driving the temp sank back down, and after 5 or so minutes of driving it was at 60'C.

    It seems now that sometimes when idling it will start to creep up, but when I move then it just drops back down.
    I turned the car on this morning 10 minutes before I was due to leave for work to de-mist etc., and when I got in the temp was still sat at 60.

    The heaters are working though now (after water pump was replaced (classic case of plastic impellers)).

    Car is a 1998 A3 1.8T AGU.

    Does this sound like t/stat?.. or sensors?.
    My mate has a VAG that hopefully I can plug it into some point this week, but I think if recommended I will go ahead and change t/stat.

    Thanks :)
    #31
  33. mazzaman
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    [Feb 6, 2013]
    Hi guys i have just changed my thermostat sensor and heh the temp goes up to 90 but now my fans wont kick in and the pipe leading from the radiator to the engine were the thermostat sits is cold is this because the thermostat is broken.

    p.s the fans work when i put the ac on.

    Please help cheers.
    #32
  34. S3 chj
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    S3 chj Member

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    [Feb 9, 2013]
    The pipe is cold because the thermostat has not opened the fans won't kick in until the bottom pipe is hot.
    #33
  35. BENJAMIN
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    BENJAMIN Active Member

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    [Feb 10, 2013]
    Classic 1.8t thermostat issue. 100%
    #34
  36. Stevorocket
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    Stevorocket New Member

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    [Jun 29, 2013]
    For info - 90 on the temperature dial on the dash is the correct running temperature (it is not "too hot")- I have several photos going back to when my car was new which prove that.
    My car A3 2.0TFSI Quattro currently reads about 72 which is caused by a faulty thermostat opening too soon.
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  37. Stevorocket
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    Stevorocket New Member

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    [Jul 8, 2013]
    This thermostat has now been replaced and the dial now reads 90c - job done. Thank you Wilcan.

    Part number is 06F 121 111 F
    #36
  38. Lavis89
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    Lavis89 Active Member

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    [Jul 8, 2013]
    this popping up has just reminded me i need to replace mine when i get the coilovers fitted next week.
    #37
  39. JudderMan
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    JudderMan Active Member

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    [Jul 9, 2013]
    I did mine a while back. Was plenty of swearing and still got a scar on my arm. But, you can loosen the stat bolts with an allen key if you don't have the various extensions that you need. Takes a while but it can be done. If you have a willing gf with skinny hands then try that, my hammer fists could barely get in there. My stat broke after fitting a new radiator, if that's any help to anyone.

    Bought mine from Audi for £30 as I'm sick of motor factors giving me duff/wrong parts and having to go back. £30 piece of mind than changing a £5-10 part a few times.
    #38
  40. Stevorocket
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    Stevorocket New Member

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    [Jul 12, 2013]
    Just did a 35 mile trip after the thermostat was fixed - car did recorded 36 mpg on A\B roads following other traffic at 40 - 60mph.

    Mines a 2.o TFSI Quattro this is at least 3mpg better than before.
    #39
  41. Epforced
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    Epforced New Member

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    [Jul 13, 2013]
    Highjacking the thread a bit, sorry :)
    My problem is a bit strange. I have a Audi S3 -02. The thermostat has been changed for a genuine one along with a new temp sensor because I got the "Error in mapped cooling system".

    Now my temp will rise so the needle is just to the left of 90 when on a highway or similar. In town it mostly reaches 90 degrees. I spoke with some people at my local Audi-dealer and they said it is fine. Aircon shows around 75-80 degrees when driving on a highway and a bit higher when I town. I havent fully checked with Vagcom since I was told not to worry, but the reading is the same there.

    I know the dash shows a very untrue reading i.e shows 90 but is everywhere from 80-105. Just a bit strange since I have never read anyone have the same scenario. MPG is fine, dunno what it is since I'm from Sweden so we calculate in L/100 km. I have about 8.5-9.2L/100 km.
    #40

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