Temperature gauge nailed to the max on 2001 Speed3

Now after owning the trusty speed3 for 6 years it's got it's first ever problem!
Riding to work today the Temp gauge went straight to the top, I know it's not an engine over heating issue as it happens too quickly. Then riding home tonight the fan didn't come on when I parked it in the garage (it always does!). That's got me worried if the fan isn't operating properly.
Does anyone have any advice on tracking down the issue, I know it's likely a faulty sensor but I'd like to be sure.

Thanks,
Philnull

[Stampy]

Check that the fan turns freely, Sometimes you can get twiggs and gunk caught up in the fan and this causes it not to turn and blow fuses :upthumb: