Q5 cooling fans running at full speed from cold

[caiss4]

I have a 3.0 TFSI petrol Q5 (62 plate). Yesterday my wife went to use the car and reported that as soon as she put the key in the dash the fans started up at full speed. I've just checked and this is indeed happening plus on start up the fans keep running. Note this is with a stone cold engine. On removing the key the fans switch off although just now I closed the door and locked the car before the fans had stopped and the next thing there is beeping from the car and the hazards flashing. That was cleared by opening and then locking again so not sure what that was about!

Anyone had any experience with this? Will it be a temp sensor or the fan controller? DIY job or trip to the dealer?

[catso]

I had an A3, 3.2L and had the fans come on full, even when ignition switched off, the only way I could stop them was to remove the fuse otherwise it would run the battery down.

Was told it was the fan controller which is inside the fan itself, done by a main dealer so not a cheap job, around £300 IIRC and a good few years back.

[caiss4]

Just to close this in case anyone searches for a similar issue the problem was sorted by my local Audi specialist. Turned out a signalling wire between the ECU and fan controller had deteriorated and gone high impedance causing the fans to run full speed. New wire spliced in and all good for a reasonable £120 labour.