2011 X5 E70 possible overheating ( No warning)

[X5E70Dazza]

Hi Guys,

Recently purchased a 2011 E70 Msport 3.0 Xdrive with 80,000 mls.
Having previously owned an E53 and also an F10.
My E70 the radiator aux fan is constantly coming on whilst driving. After about 10 mins of driving it will come on and stay on until ignition is switched off. I loaded up the temp gauge via the hidden menu in the instrument panel and my cars averaging 100 degrees celsius with the maximum it got to being 104 C.
First of all, is this the engine oil temp or the coolant temp?
I am not getting any errors or messages regarding overheating. But I'm stumped as to why the fan is always coming on. Could my water pump be on the way out?
Any simple ways of testing? Is this a normal operating temperature and if so why is the fan constantly coming on?
The fan turns off when I turn the ignition off. its also not blowing hot air out when waving hand in front of it.
Any info much appreciated thanks guys