Coolant temp sensor

[den911]

Hi as part of my quest to sort my slight niggle with my fluctuating gauge I started with my temp sensor as it arrived today and fitting was pretty straight forward ,here is pic of the old one that looks a tad worn...May not be the problem but for price and ease of fitting it’s worth doing...

 

[den911]

Update on sensor fitting ,prior to fitting the new sensor I noticed that a heavy (ish) foot was needed setting off and it just wasn't as smooth as I thought would be. also sounded like a tractor setting off ..... Also only having the car a week I was not sure what was normal and what was not. I knew I had a niggling issue with temp gauge hitting 90c and then dropping to around 80c and going back so first port of call was a service which I did and then I ordered the sensor and a new thermostat ,the sensor was first to arrive which I fitted pretty quick,i then got a message from Audi to say the thermostat was ready to pick up so a good excuse for a test drive with new sensor in, and I must say setting off was a lot smoother and felt a lot more refined I was convinced a £10 part could not cause such a issue but after 20 miles the gauge was behaving at 90c both when on motorway and off motorway ,I know I need a longer run to prove it's all ok but I could tell going through the gears the car was much smoother ...I do have the thermostat booked in tomorrow so it makes sense to have it done ,as said the proof of the fix is in a longer drive but my gut feeling after the first drive after fitting is positive ...

 

[den911]

Spoke too soon it’s back to playing games but car is definitely running better ....Thermostat tomorrow

 

[ab1702]

Spoke too soon it’s back to playing games but car is definitely running better ....Thermostat tomorrow

Keep us updated as I have the exact same problem.
What car you got, engine etc?

 

[den911]

Keep us updated as I have the exact same problem.
What car you got, engine etc?

I have a A3 cab 1.6tdi 2011 ...And it's one annoying niggly pain ,it gets up to temp and does sits there then sometimes as soon as i drop speed from 50/60 mph to 30mph it can go down but then a few mins later it will pop back up to 90 ..Never over 90 though ..As soon as i get the thermo on i can update ,if it's not the thermostst all i can think off is the actual gauge itself on the instrument cluster but i suppose that would either work or not work

 

[ab1702]

I have a A3 cab 1.6tdi 2011 ...And it's one annoying niggly pain ,it gets up to temp and does sits there then sometimes as soon as i drop speed from 50/60 mph to 30mph it can go down but then a few mins later it will pop back up to 90 ..Never over 90 though ..As soon as i get the thermo on i can update ,if it's not the thermostst all i can think off is the actual gauge itself on the instrument cluster but i suppose that would either work or not work

I’ve got the exact same symptoms, mines a 2010 170 tdi.
I was quite sure the coolant temp sensor wouldn’t sort your problem as I’ve seen a few threads about the same problem and that never sorts it.
I’ve never seen a resolution though.
I mentioned it to the bloke at the garage I use and he reckoned it would be the thermostat but I’ve just never got round to doing it or having him do it.
I have also heard that these cars may have 2 thermostats?!

 

[prt57]

I am thinking it is the thermostat that is at fault with the fluctuating gauge. We have had 2 cars over the years where this has been the fix.

Interestingly last year I had a wired problem with my S3.
I was upgrading the gear cable shifter mechanism and so unplugged the lead to the temperature sensor above the gearbox. After reattaching the lead, both engine bay fans came on full blast when the ignition was turned on. The sensor must have had a dodgy internal fault as when I replaced it with a new one the fans were back to normal.

 

[den911]

Just been told by the mechanic that the thermostat I have been given is not the right one ,ok so I go to Audi and explain they check the parts page and tell me it shows as being the right one but there is also another one this now gets me confused and he shows me another one .....Anyway I went back to the mechanic which the original and another one I ordered, he says the canister looking one is correct and the first on he can’t see on the car .....can anyone shed. My light on this ..

 

[den911]

 

[den911]

 

[den911]

Sorry about the missed focus ,no matter what i did it just wouldn't lock on ...This is just to the right just below the alternator its the only thing that looks like a thermostat housing to me ..

 

[den911]

Another update.....Been back to Audi and exchanged the Thermostat Housing with the correct one ,book time for job is 2.5 hours ...
Hopefully it will get done in the morning so it's one less possibility to eliminate ..

 

[den911]

OK...Looks like this could be the final update on the temp gauge underheating low mpg i have been having..
Got the car back last night done over 100miles and the temp gauge is sitting at 90c with a imrovement on the avg mpg ...

 

[abmat]

With or without thermostat being done? Good news it’s sorted though.

 

[den911]

Sorry didn't realise i had ommited that information,yes it looks like it was the Thermostat a sealed unit £31 fro Audi

 

[baderlfc]

Had exact same issue with my S3 when I bought it, had new thermostat fitted when the garage were doing cambelt/water pump.. problem solved.