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Audi A3 Temp Sensor Issue

Discussion in 'A3/S3 Forum (8L Chassis)' started by seanseansean, Feb 16, 2013.

  1. seanseansean
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    seanseansean New Member

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    Audi a3 1997 AKL engine, 1.6

    Temp sensor in car sits at bottom left (60 Deg) when driving but when you leave the car to idle it goes upto middle (90 Deg).

    This is a blue sensor 4 pin blue,

    Fan comes on when it gets to hot and all pipes feel warm,

    I have bled the system for air in the coolant.

    No over heating issues, Not fault codes apart from the knock sensor.

    Any ideas?

    Thanks
    #1
  2. <tuffty/>
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    <tuffty/> Badger 5 Edition Staff Member Moderator

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    Thermostat....

    <tuffty/>
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  3. seanseansean
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    seanseansean New Member

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    Its not overheating tho,

    The thermostate only opens and closes when hot or cold - if it breaks then it usually overheats the engine as it gets stuck in one place.

    This is what I think unless a mechanic may know diff?

    Thanks
    #3
  4. <tuffty/>
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    <tuffty/> Badger 5 Edition Staff Member Moderator

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    A dodgy thermostat normally sticks open not closed... the stat helps regulate flow through the radiator as well as blocking flow while the engine warms up...

    Have you changed the sensor? its fairly common for both the stat and the sensor to fail.... if you have access to VCDS its probably worth checking the temp on both the engine module and the instruments module as the CTS two sensors feed these and its not uncommon for one of the sensors to be faulty and the other to be fine... but your issue sounds more like a dodgy stat...

    <tuffty/>
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  5. seanseansean
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    seanseansean New Member

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    No probs I appreciate your help,

    New Thermostat has been ordered and ill replace it this sat,

    Ill post back with the update,

    Thanks
    #5
  6. phil miller
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    phil miller Member

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    Stats are designed to fail in the open position, change it and your problem is gone :) fit genuine tho
    #6
  7. seanseansean
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    seanseansean New Member

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    Should be getting the part Thur/Fri - Then fitting on Sat,

    Anything to watch out for? - Seems a pretty simple task from what Ive read.

    Cheers
    #7
  8. Munch
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    Munch Member

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    I done mine last Thursday, after suffering exactly the same proble as your self. The only thing to look out for it the brittle plastic dipstick holder, despite knowing the potential issue and being silly careful, I still managed to snap mine.
    Is potentially a 15 minute job to change it, just make sure you have a 10mm socket, a knuckle type connector and patience, lol
    #8
  9. seanseansean
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    seanseansean New Member

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    Just an update everyone, the thermostat aint coming till Mon-tue now and I am down in Derby for training with my work, I am back on Thur,

    Planning do do the change next weekend now,

    Will keep you posted.

    Cheers
    #9
  10. Blackie_No1
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    Blackie_No1 New Member

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    Mine was doing the same until I fitted a new thermostat, now running perfect, knuckle joint would defo make it easier, I had to do the bottom bolt with a 10mm spanner, patience wore thin after a while!!
    #10
  11. seanseansean
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    seanseansean New Member

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    Hi there,

    New thermo fitted, still same problem,

    On idle it goes upto 90 Deg, when out driving it drops down to 60 Deg,

    Tested old Thermo in a cup of boiling water and it opens and closes no problem,

    So that rules the thermo out, plus it has a new temp sensor, only fault code is the knock sensor.

    Any ideas ????????????? :(
    #11
  12. seanseansean
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    seanseansean New Member

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    Anyone Lol ?

    HELP PLEASE :D
    #12
  13. seanseansean
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    seanseansean New Member

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    Does anyone have the wiring diagram for the a3?

    Thanks
    #13
  14. dualmono21
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    dualmono21 Active Member

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    could be the impeller off the waterpump has failed
    alot of the impellers are simply glued and designed to fail if the bearings in the waterpump fail
    if however the glue has broken down and the impeller has come adrift but the waterpump is still ok
    the car will come upto temperature and the fans will come on to cool it down
    but when driving normally the temperature will go up and down as the cooling effect of the air will cool the exposed parts of the engine
    #14
  15. seanseansean
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    seanseansean New Member

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    Would this not cause it to overheat?

    as the car sits idle, it goes upto temp no probs and sits at 90 - I turn the blower on in the car and the temp drops down,

    Car never overheats though,

    A broken water pump not cause more issues than what ive got?

    Is there a way to look and see if the propeller is intack?

    Thanks
    #15
  16. seanseansean
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    seanseansean New Member

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    PLEASE MARK THIS AS SOLVED!

    I GOT SOLD A DODGY THERMOSTAT - NEW ONE FITTED ALL WORKING WELL

    NOW FOR A NEW KNOCK SENSOR AND HOPFULLY ILL BE DONE :D
    #16

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