High coolant temps and fans running but no overheating resolved

[Enjay999]

Just thought I'd put a post in here in case anyone is doing a google search for the same problem I just had.

2007 seat alhmabra 2L tdi, had the temp gauge reading a bit high and radiator fans coming on which isn't normal for this car even in mid summer. Every time I checked the upper hose wasn't extra hot and there wasn't extra pressure, also coolant level looked good.

I went out one evening after the engine had cooled down, started the car up and within less than a minute the gauge was reading halfway but engine was still pretty cold. So I got the computer out and plugged up, ecu was seeing about 46C then a few seconds later it had jumped to about 84C so I knew the sensor was wonky.

Anyway got a new sensor, fitted it and all is back to normal. Although there is apparently a radiator fan switch down the bottom of the lower radiator hose the fans were coming on when that hose was barely warm. It looks like the ecu must use the coolant temperature sensor or a separate fan controller somewhere to operate the fans despite the fan switch.

Hopefully that'll help others searching,