Radiator fans going on / off at all hours

Howdy  y'all ... this has popped up here and there from time to time on both here and other VW / Audi forums. Both fans on my 2012 1.4TSI Octavia come on suddenly and spool up to full power when the car is parked / cold. Cycle through full power for a few mins. and then down and then cycle up again. It's NOT a diesel so that rules out any issues with DPF.

From what I've read so far it looks like either the coolant temp. sensor ( I got a grey 2 pin type ) or fan control module built into the hub of the big fan. Fuses are all fine and I can't seem to find any 'relay' associated with the fans / fan control. This problem seems to be 'not uncommon' in VAG cars but if anyone has any ideas as to what might be the definitive cause for this on a 2009-2012 1.4TSI engine VAG car, please do tell  ( :