# temp gauge a little wacky...



## turbott920 (Nov 13, 2007)

For the past couple weeks my tempature gauge has been kinda sporadic. It will be working fine one minute then suddenly drop all the way to "C" stay down for any given amount of time, be it one second or half an hour (no real pattern) It seems as tho everything is performing properly, my climate control doesn't act as if it's cold or anything like that but it does make me a bit concerned. Has anyone had a similar problem or have ideas of what the problem/solution is?
Thanks in advance.


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## Blue TTop (Nov 21, 2003)

*Re: temp gauge a little wacky... (turbott920)*

Your TT is a 2001 and it likely does not have the upgraded temp. sensor. If yours is black, you need to change it to the green temp. sensor located here - 








This is the upgraded temp. sensor (part#059 919 501A, O-Ring N 903 168 02) - 








Make damn sure the car is cold if you pull this out!!!!


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## bauch1425 (Jun 29, 2006)

*Re: temp gauge a little wacky... (Blue TTop)*

Definitely try changing out the temp sensor, even if it has already been upgraded to a green top - they can still fail although its not as likely.
The next bet would be the cluster. They go out extremely often and aren't cheap. AOA won't recall them either (like Audi UK has)... go figure.


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## turbott920 (Nov 13, 2007)

*Re: temp gauge a little wacky... (bauch1425)*

Thanks for the help guy's...I'll go take a look after the Packer game GO PACK http://****************.com/smile/emthup.gif http://****************.com/smile/emthup.gif http://****************.com/smile/emthup.gif


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## Midnight_1.8T (Jul 11, 2002)

*Re: temp gauge a little wacky... (turbott920)*

could be a number of things. 

i saw that it snowed pretty good tonight over there. the drop in temp can be just from the cold air outside. here in pa when we got hit with the 5* days....my temp gauge was all over the f'ng place. 

the other issue could be a thermo problem or a pump issue. water pumps in the motors are usually plastic and the blades actually crack and fall apart in the motor at times. this would cause a spike in temp since the coolant can not be spread efficiently. as far as a thermo issue....its highly unlikely they would fail. but the reason i mentioned it is because if you are around the time your timing belt should be changed ie....60-75k...you should also replace both of these while you are replacing the timing belt.
again.....my pick is just the fluctuating temperaters of the outside air...nothing to really worry about until you actually see over the half way mark or the light comes on. 
if you have a vag com....check to see if you have any codes and that will tell you if the temp sensor is working correctly...if you just want to forget about the problem completely just drop the seven bucks on a green top....it will help with a little more timing and may cure your problem in the end.


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## my own style tt (Sep 2, 2007)

*Re: temp gauge a little wacky... (turbott920)*

Just did my Thermostat It was a big PITA but everything worked out


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## bauch1425 (Jun 29, 2006)

*Re: temp gauge a little wacky... (Midnight_1.8T)*

Good suggestion although in this case I don't believe its the water pump nor the thermostat to be worried about here. Outside air shoudln't really affect the operating temperature of the engine either - that's the job of the thermostat - it should keep it close to 90 deg C (+ or - 5 deg C) at all times.
A failing water pump will often times cause more overheating like symptoms. 
The 1.8t thermostats (which aren't too uncommon to fail) usually stick in the open position in which case the engine won't reach operating temperatures a lot of the time. The temperature gauge will rise up and down however it will take a few seconds for the needle to move and the movements will not be at all jerky.
I would replace your temp sensor, they're cheap and easy to do.
After that I'd unfortunately have to say that your instrument cluster is probably on its way out. 
Edit: I changed mine a couple of months ago, major pain in the a** to do because of space constraints. I don't think you have to worry about that here though. If you temperature gauge bounces from "C" to the middle in one of those instances where it did it in a second - its not going to be the thermostat, or water pump - i.e. nothing mechanical. It would be something electrical (temperature sender or instrument cluster).


_Modified by bauch1425 at 8:57 PM 1-12-2008_


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## lonestart (Jan 5, 2007)

*Re: temp gauge a little wacky... (Blue TTop)*


_Quote, originally posted by *Blue TTop* »_Your TT is a 2001 and it likely does not have the upgraded temp. sensor. If yours is black, you need to change it to the green temp. sensor located here - 








This is the upgraded temp. sensor (part#059 919 501A, O-Ring N 903 168 02) - 
Make damn sure the car is cold if you pull this out!!!!

Where can I get one of the 3 point vac line connectors like in the picture?


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## Gina02 (Feb 27, 2008)

*Re: temp gauge a little wacky... (turbott920)*

Hi there .. I have recently been experiencing a similar problem with my 02' roadster .. had the temp sensor changed out yet the gauge is still slowly fluctuating between the center notch and the notch below... the heater is operating ok and all other gauges are functioning properly.. I am at 62,000 mi had a new water pump and timing belt at around 50,000 mark. .. just curious to know if and how your prob resolved.


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## bauch1425 (Jun 29, 2006)

*Re: temp gauge a little wacky... (Gina02)*

I'm thinking yours may be the thermostat. They commonly fail in the open position so your fluctuating one notch below falls in line. Check the HVAC diagnostics - 49C will give you your operating temps. If those match with what the cluster says then its your thermostat. The Temps should be 90 deg C


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## Gina02 (Feb 27, 2008)

ok thanks...


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## turbott920 (Nov 13, 2007)

*Re: temp gauge a little wacky... (Gina02)*


_Quote, originally posted by *Gina02* »_Hi there .. I have recently been experiencing a similar problem with my 02' roadster .. had the temp sensor changed out yet the gauge is still slowly fluctuating between the center notch and the notch below... the heater is operating ok and all other gauges are functioning properly.. I am at 62,000 mi had a new water pump and timing belt at around 50,000 mark. .. just curious to know if and how your prob resolved. 

I ended up getting a full timing belt kit done...along with that came a new thermostat, ever since then I have had no problems what so ever and I am still with the black temp sensor.


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