Radiator fan on constantly when running

[rpccy]

Hi all,

I hope I’m posting this in the right place. I have a 2001 b6 saloon with the 2.0 petrol (not fsi), recently the radiator fan (larger, passenger side one) has been kicking in from startup constantly. There’s zero water in the ecu and the fan switches off when the car is turned off. Both coolant temperature sensors have been replaced recently. Does anyone have any ideas what this might be? I was considering changing the fan switch but would rather have it pinned down first before changing parts.
Thanks

Forgot to say that the engine temperature dial on the dash isn’t working (or sometimes randomly comes to life then returns to the ‘cold’ position).

[arman123]

First thing you should do is get a scan done vcds to see if any codes.

What make coolant temp sensor did you use because if you temp dial is erratic it could be the coolant sensor if duff.

[Crasher]

Probably the radiator fan control unit which is hard wired into the fan harness.

[rpccy]

Thanks for the replies. I had the car scanned a little while ago and it said something about ‘system voltage low’, referring to the cooling system, but I haven’t used the car since. I’ll have to go back to the garage then by the sounds of it to investigate further. Is the fan control unit a tricky job?

[Crasher]

Bit of a fiddle, the wires have to be de and re-soldered.