I have a 2001 tt 180hp. I have changed the thermostat, coolant temp sensor, radiator fan switch, and the fan control module. The water pump was changed about 8 months ago. When running my gauge is just below the halfway mark, but if i stop and idle for 30 seconds or more the needle will creep up to the notch above halfway. The fans will come on, but i question if they are coming on quickly enough and staying on long enough. The fans also are not coming on when I turn off the car although the temp is high enough that they should be on. I used a jumper wire on the fan switch connector and can get low and high speed. I am out of ideas and would love some suggestions.

 

Flushed the radiator last night and changed out the fan switch even though the one I replaced was a new one from NAPA. May have lucked out as it did not overheat this AM on the way to work with plenty of bumper to bumper driving. Will let you know in a couple of days if this was a cure or just another disappointment.

 

No luck! Time to take it to a shop for a real diagnosis...

 

Any update? I'm having the same exact issues with my 2000 tt, I bought in November with 100k on the OD.

I'm getting ready to replace the radiator and all the temp sensors. right before winter I had the water pump, tstat and hoses replaced. The mechanic told me the car had Non g12 coolant in the system. He did a flush but the only thing I didn't swap out was the radiator.

Let us know. Thanks.

 

OK, just got the car back after a couple of weeks at the garage. It is perfect now, but the solution was a bad instrument cluster causing it to appear as if it was overheating. The diagnostic proved everything I did was working correctly so while some of it probably wasn't necessary at least i now have a bunch of new stuff under the hood. So, $771.00 and a rebuilt instrument cluster later and all is good. Normal guys don't have that diagnostic equipment at home so if you eliminate potential issues and can't get it corrected a good mechanic is the sure answer. Start with the temp sensor and fan switch as they are fairly cheap and easy, but that radiator is going to test your patience. By the way, the instrument cluster is comparatively easy to deal with. I just figured it was easier to sit back, enjoy a beer, and let someone else have fun working on my TT for a while. Welcome to TT ownership my friend. Good luck!

 

Thanks for the update.

I'm aware of the audi cluster issues. But according to the car fox report, mine was replaced. So I'm heading up the radiator swap and all the sensors and fan switch this Sunday. I sat back last time with the beer and it cost me 2k for the 100k maintenance work for the timing belt, water pump and bunch of other stuff to save this tt when I bought it. I'll let you know my out come on Monday. Thx

 

radiator coolant temp fan switch controls continuous fan low speed On at 90°C but high speed is only controlled by the AC at 100°C when AC is on. Temp switch on the engine block sends signal to dash guage which it not gradiated but jumps one notch past verticle at 95°C.

Once engine warms up both fans should come on and run continuously on the quiet low speed.