Coolant temperature sensor TDI90

Nope - commute home for 35 minutes and it reached the steadying heights of 62 degrees by the end of the commute.

Surely that would only leave the thermostat now then?
 
hmmmmmm - most odd......

Not the nicest test, but on the commute into work tomorrow morning, don't use the heating system at all, unless you need to demist, and then only use it briefly and turn it off again aferwards.

It obviously matters what the journey is like - a 35 minute journey in London at 8.30am between Sheperds Bush and West Kensington with an ambient temperature of 5°C is unlikely to raise the engine temperature above 60°C, where as a journey on the M62 driving at 70mph for 10 minutes with the same ambient temp will see the engine at a steady 90°C.

There may still be air in the system, but it might also be that the thermostat is not closing or because it's faulty or wrongly fitted.
There are different temperature thermostats too, I believe, but if I remember correctly they only vary by a few °C, so doubtful if that is the issue.

Unfortunately this issue is really difficult to track down as YOU didn't do the work yourself, and you're reliant on the workshop technician being "on his metal" when working on your car.

It it were me, I'd try bleeding any further air first - if temp gauge rises to 90°C every time the expansion cap is off I think that suggests the sensor is working as it should, and I'd then remove the thermostat and check it was fitted correctly and replace it - then test and see what occurs.
 
Thanks for the advice Jeff, it really is appreciated.
Has got all the symptoms of a duff thermostat, yes I know its a new Audi one, but that should never rule it out as a likely cause of the problem
I have got the last 4 or 5 thermostats from EuroCarParts and the stat looks identical to the Audi once that have been coming out (other than the Audi VW logo being missing, other than that identical in EVERY way)
They are £4:20 so well worth chucking one in to see if it makes any difference
Cheers,
Paul
 
Has got all the symptoms of a duff thermostat, yes I know its a new Audi one, but that should never rule it out as a likely cause of the problem
I have got the last 4 or 5 thermostats from EuroCarParts and the stat looks identical to the Audi once that have been coming out (other than the Audi VW logo being missing, other than that identical in EVERY way)
They are £4:20 so well worth chucking one in to see if it makes any difference
Cheers,
Paul

I think that's the way I'll go Paul and then try to get a refund on the £30 Audi one once I know that fixes the issue. Not what I'd hoped to be doing this weekend but needs must.
 
Has got all the symptoms of a duff thermostat, yes I know its a new Audi one, but that should never rule it out as a likely cause of the problem
I have got the last 4 or 5 thermostats from EuroCarParts and the stat looks identical to the Audi once that have been coming out (other than the Audi VW logo being missing, other than that identical in EVERY way)
They are £4:20 so well worth chucking one in to see if it makes any difference
Cheers,
Paul

I think that's the way I'll go Paul and then try to get a refund on the £30 Audi one once I know that fixes the issue. Not what I'd hoped to be doing this weekend but needs must.

Tis the way it goes some times Steve


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Just to add something here guys..............the temp on the 05 plate silver one I drive has never reached 90 for about two months but over the last two days with the temp outside going up I noticed the temp gauge reaching 80 or 90. ive always turned the temp in the car to HI and it has always reached hot in the vents.... even when the gauge is at rock bottom. Now heres a thing..............in the green A2, (the wife drives it) she always moans that the car never gets warm but the temp on the dash reaches 90 within a couple of miles.....explain that one...........LOL.
 
Just to add something here guys..............the temp on the 05 plate silver one I drive has never reached 90 for about two months but over the last two days with the temp outside going up I noticed the temp gauge reaching 80 or 90. ive always turned the temp in the car to HI and it has always reached hot in the vents.... even when the gauge is at rock bottom. Now heres a thing..............in the green A2, (the wife drives it) she always moans that the car never gets warm but the temp on the dash reaches 90 within a couple of miles.....explain that one...........LOL.
Not having a TDI I rarely read TDI threads, but surely your wife's car is screaming out partially blocked heat exchanger matrix not supplying full heat to the cabin. - Andy
 
Now heres a thing..............in the green A2, (the wife drives it) she always moans that the car never gets warm but the temp on the dash reaches 90 within a couple of miles.....explain that one...........LOL.

It's possible one of the motorised heater flaps is stuck as this could prevent hot air from the heater matrix reaching the cabin.

Cheers Spike
 
Has got all the symptoms of a duff thermostat, yes I know its a new Audi one, but that should never rule it out as a likely cause of the problem
I have got the last 4 or 5 thermostats from EuroCarParts and the stat looks identical to the Audi once that have been coming out (other than the Audi VW logo being missing, other than that identical in EVERY way)
They are £4:20 so well worth chucking one in to see if it makes any difference
Cheers,
Paul

Hi Paul,
Do you have the part number of the one you got from ECP?
I checked using our reg and there are 2 listed, one shows the seal the other doesn't but interestingly the one that doesn't show it mentions it in the fitment detail:
Circoli Thermostat 209440040
Circoli Thermostat 209660160

Thanks,
John
 
no sorry I don't have the part number, I just give ECP the reg number and they provide the correct stat
Cheers,
 
Have you managed to resolve this? It seems like mine is behaving in exactly the same way, even down to me leaving the coolant cap off to clear any airlock
 
I've got a new thermostat on the way from eurocarparts. I haven't driven the car far for a week or so as I've been on holidays.
 
I ordered both the Circoli stats listed for the A2, £8.69 delivered - see photos.
Anyone got a photo of an original to compare, I'll be able to do it myself when I take my Dads one out but it would be handy to see the difference up front. The original from TPS was priced at £28.52.
Both are rated at 87degC
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the one I used on my BHC back at Easter was the 209440040. It came with the O-ring and made a dramatic improvement on the warming up rate.
 
This sounds like it could be the problem I identified on my 1.4L petrol and I now suspect was also present in the 1.4 75bhp TDI that I used to own, so perhaps quite common? I mentioned it here https://www.a2oc.net/community/inde...moke-when-starting-from-cold-in-winter.36279/

The green 4-pin coolant temperature sensor, which can only have been fitted by the H R Owen Audi dealer in Watford - no other garage ever worked on the car until then, had pins that were too thin for the connector. Made for intermittent connection on BOTH circuits, dash gauge and ECU feed, though not necessarily at the same time. The dash gauge problem would self-resolve from time to time, presumably due to vibration.

I got this as a replacement https://www.ebay.co.uk/itm/Audi-Wat...e:Audi&hash=item27d1161367:g:HC0AAOSwlmhbNQmm and could see by eye that the pins were much thicker. Problem went away.

Btw you can rule out thermostat fault quickly if you have a thermocouple handy, just stick it in the coolant in the top up reservoir. My cheapo Hilka multi-meter that I bought from Argos years ago came with a thermocouple. In my case I could see that whatever the temperature the dash gauge was showing, the thermocouple always measured 85-87 deg.
 
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