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1999 1.9 TDi temp gauge not moving and heating only 'warm'

martin_addlestone Feb 8, 2013

  1. Hi guys,
    I currently have a 1.8 petrol and although she is a bit slow heating up but when she does she sits lovely at the half way mark and blows toastie hot air onto my feet.

    I am looking this weekend at buying an old 1.9 Tdi on a W plate (it's a red i, i'm told tha means 115bhp?) as something to get us through some tough financial months ahead. It's a B5 auto with Tip avant, starts and drives well etc but has done 170k.

    My only concern is that the temp gauge doesn't move at all, and the air coming from the vents is only 'warm', definitely not as warm as every other car I have owned.

    It sounds like 'stat, or maybe temp sender, which I am fine with if so, but just wondered if there are any serious issues that could manifest in this way and cost me an arm and a leg?


  2. B5NUT

    B5NUT Well-Known Member VCDS Map User quattro Audi A6 Audi Avant Owner Group s tronic S-line owners group

    If you don't have access to a diagnostic reader then I would change both, there is not much cost and both are known to fail.
  3. Thanks B5Nut, that was kind of the plan - just before I part with the cash to buy the car wanted to be sure there wasn't any more expensive issue that may be the cause.

  4. Bradderz_1988

    Bradderz_1988 Dont replace it, Upgrade it !!

    Just replace the stat and it will be fine.
  5. Thanks Bradderz - Thing I'll go offer him a grand and see if he bits - you guys have given me the reconfirmation I needed - cheers chaps!
  6. jas828

    jas828 Member

    my 1999 1.9 avg 110bhp was like that when when i bought 2 months ago now within 6-7 miles of drivin nice and toasty warm after changing stat
  7. Bradderz_1988

    Bradderz_1988 Dont replace it, Upgrade it !!

    Yeah the differance in heat is very noticable and when the weather is like it is now its all ways good to get them on full blast :)
  8. So - Car is with my mechanic being done now, temp sender and stat, but he bout the sender from Audi and they gave him a diagram of where it should be, and it does not seem to be correct, he has found a temp sensor near the front close to the PAS pump, but wonders if there is maybe a second one given their diagram - any ideas?

    Also he thinks that the temp sender may also be part of the problem with the cold start, i.e. if it is broken
    it may not be sending the right signal to the ECU to turn on the glow plugs when cold - is that possible on these engines?

    it's the 115 PD by the way

  9. aragorn

    aragorn "Stick a V8 in it!" Staff Member Moderator VCDS Map User

    Why are you randomly changing components? The thermostat is a very common fault and almost every car this age needs one. The temp sensor rarely fails in my experience, yet everyone seems to rush in and change both?!

    The "sensor" near the pas pump is a switch for the electric fan, nothing more.

    The main coolant sensor for the engine management and dash cluster is on the rear of the cylinder head. Follow the top radiator hose and it should lead to a plastic housing, with the sensor in. The sensor should be green, with four pins.
  10. Bradderz_1988

    Bradderz_1988 Dont replace it, Upgrade it !!

    As above i only replaced my temp sensor due to a leaking housing so just order the sensor whilst i was doing the job !!
  11. Sorry for the delay guys, been a hectic few days. So first of all thanks for your input, in hind sight I agree rushing in to changing both may have been a waste of cash, luckily it was a cheap enough part and ruled out a theory my mechanic had that the sender may some how be affecting the cold start.

    So, heating now sorted, she gets up to normal temp after about 3 - 5 miles and blows warm air into the cabin - finally.

    But, the cold start issue not solved. He claims to have tested the power to the glow plugs and the plugs themselves and says both are OK - He has a feeling it could be a fuel related issue - i.e. when stood for a prolonged period of time somehow the fuel is running back down the lines, or air is creeping in ect and as there is no electric pump in the tank (according to Audi yesterday) the car needs to turn over for about 15 - 20 seconds before gradually chugging into life. Yesterday he changed the fuel filter which looked pretty old, had a little water in and was quite loosely fitted (unscrewed very easily) and today he will try to start her from cold again. If there is still an issue he has arranged to take it to his friend garage and run it through a diagnostics machine (maybe this should have been the first port of call to be honest, another lesson learned for me there!)

    Will keep you in the loop of whats going on, really want to get this solved as no car is becoming a pain.


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