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Thread: temperature warning light

  1. #1
    Join Date
    Sep 2008
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    Ulverston, Cumbria
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    89

    temperature warning light

    The other day the temperature warning light came on, in the centre drivers information display. Only thing was that it was early morning and the engine was stone cold - I'd only driven 50 metres at most. It flashed a few times and then went away with the usual fuel consumption etc figures showing. Turned the engine off, checked that there had been no coolant leakage, also noted that the temperature gauge showed cold. Drove on, no warning light, and the gauge gradually got up to 90 degrees as usual. No problems since.

    Just a glitch ?

  2. #2
    Join Date
    Apr 2009
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    Staines, Middlesex, UK
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    Not many responses to your issue!

    But I guess that this is probably because not many (if any) would have experienced that issue.

    The ONLY time I have seen the red temperature warning was when the car got REALLY hot, stuck in traffic with an outside temperature of 39 and the coolant fan was not working!!

    Is yours a "glitch" ??? I don't believe in glitches really, but what else could it be?

    The only other thing would be a short or bad connection, but I am not sure that the warning would come on even if you disconnected the sender.

    I suppose the only thing you can do is to treat it as a glitch and hope it doesn't return?

    Steve B
    White (non-Factory) TDI 90 - BOSE, MFSW, DIS, cruise, Headlamp washers, rear cupholders, Votex style rear spoiler, Heated (twist) leather, double DIN, DIS, rear Power Socket, false floor, Auto headlights, LED interior bulbs, 18" x 8" - 9 Spoke "Sport" alloys on new 215 35 18 Yokohamas, Auto dimming mirror, heated door mirrors, 4 electric windows, Front fogs.

    VCDS and Key programming service, Votex Jacking point covers (3d copies) available.


  3. #3
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    Sep 2008
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    Ulverston, Cumbria
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    Quote Originally Posted by Birchall View Post
    Not many responses to your issue!

    But I guess that this is probably because not many (if any) would have experienced that issue.

    The ONLY time I have seen the red temperature warning was when the car got REALLY hot, stuck in traffic with an outside temperature of 39 and the coolant fan was not working!!

    Is yours a "glitch" ??? I don't believe in glitches really, but what else could it be?

    The only other thing would be a short or bad connection, but I am not sure that the warning would come on even if you disconnected the sender.

    I suppose the only thing you can do is to treat it as a glitch and hope it doesn't return?

    Steve B
    Thanks Steve, it was an odd one. No repeats yet and it's a week on. The only other thing worth mentioning was that I'd had the thermostat replaced (the temperature gauge had been showing around 70 degrees and I had already had the temperature sender replaced) - but that had been a couple of weeks previously.

    Incidentally the fuel consumption has improved now there's a correctly working thermostat.

  4. #4
    Join Date
    Sep 2008
    Location
    Ulverston, Cumbria
    Posts
    89
    and again today, not having used the car for a couple of days. Plenty of coolant. Faulty temperature sender? Airlock in the system somewhere?

  5. #5
    Join Date
    Apr 2009
    Location
    Staines, Middlesex, UK
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    Quote Originally Posted by trevorswaine View Post
    and again today, not having used the car for a couple of days. Plenty of coolant. Faulty temperature sender? Airlock in the system somewhere?
    It is unlikely to be an air lock, because it would still take many minutes before the temperature was hot enough to set off the warning.

    But there would be no harm just (from cold) remove the coolant filler cap, ensure that the level is correct, run the engine until operating temperature with the cap off and stop the engine, then check the level again.

    That is one way to "bleed" the system.

    Check the connector on the temperature sender, look inside to see if there is any moisture (that MIGHT be the cause). Spray a little WD40 inside the connector and on the sender contacts.

    If it was coming on after 10 minutes of driving then it might have been an air lock, but I would guess that it is water / moisture inside the connection.

    Steve B
    White (non-Factory) TDI 90 - BOSE, MFSW, DIS, cruise, Headlamp washers, rear cupholders, Votex style rear spoiler, Heated (twist) leather, double DIN, DIS, rear Power Socket, false floor, Auto headlights, LED interior bulbs, 18" x 8" - 9 Spoke "Sport" alloys on new 215 35 18 Yokohamas, Auto dimming mirror, heated door mirrors, 4 electric windows, Front fogs.

    VCDS and Key programming service, Votex Jacking point covers (3d copies) available.


  6. Users that liked this post:

    trevorswaine (13-10-2017)

  7. #6
    Join Date
    Apr 2012
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    Altrincham.
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    Odd, I had exactlythe same symptoms, cold engine and bong red temp warning. I changed the coolant temp sensor, and the problem went away.

  8. 2 users that liked this post:

    Special edition (12-10-2017), trevorswaine (13-10-2017)

  9. #7
    Join Date
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    St Annes on the Sea
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    yes I am thinking coolant temp sender is the most likely cause, not a dear part to replace to at least eliminate the possibility
    Other possibility is a fractured wire in the loom somewhere (I hope not as that will be a mare to find)
    Paul (Depronman)
    1.4 TDI 2001 287,347 miles and still going strong

  10. #8
    Join Date
    Jan 2014
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    Wakefield, Yorkshire.
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    2,842
    You can buy a non original coolant temperature sensor on ebay for under a tenner. My local mechanic didn't exactly rate them so I bought one from an Audi dealer for 47 including two spare plastic clips (they fly off and get lost) and the rubber seal.
    Last edited by Special edition; 12-10-2017 at 09:12 PM.
    Cherry Red Tdi 90

  11. #9
    Join Date
    Aug 2015
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    St Annes on the Sea
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    Euro car parts under a 10 and have worked perfectly for my, 3 used so far the oldest one being fitted some 3 years ago, still working perfectly
    I'm not saying they are as good as the Audi OEM ones, but do work well and appear to last OK
    Cheers,
    Paul (Depronman)
    1.4 TDI 2001 287,347 miles and still going strong

  12. Users that liked this post:

    Special edition (13-10-2017)

  13. #10
    Join Date
    Aug 2012
    Location
    Alton, Hampshire, United Kingdom
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    438
    Hi,

    its also worth considering that the symbol will come up if a low coolant level has been detected.
    Assuming that the coolant level isn't very close to the minimum line and there aren't any problems with the head gasket then the low coolant alarm can be triggered by corrosion on the electrical terminals. A common problem is that the place where the level sensor terminals exit the coolant expansion tank can start to leak when the tank ages. This allows coolant to get inside the connector and cause the terminals to become corroded. The expansion tanks on both my A2's have needed to be replaced for this reason. If you remove the plug on the expansion tank you can check if it is wet and examine the condition of the terminals on the connector and the tank.

    regards

    Andrew

  14. 3 users that liked this post:

    depronman (13-10-2017), johnyfartbox (12-10-2017), trevorswaine (13-10-2017)

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