What could be causing the radiator fan to switch on too often on my 2008 Jaguar S-Type?

I have a 2008 Jaguar S-Type 2.7 diesel with 27,000 miles on the clock. Of late it seems to me that the radiator fan operates much too frequently, almost always when the car stops for traffic lights, when I back it into the garage, when I start it up in the morning and switch if off in the driveway 30 feet later (which I generally avoid doing), even when on the move from time to time as when, this past weekend, driving through Liverpool. The level of coolant in the radiator is correct, and the temperature gauge routinely indicates correct normal running temperature. So what, please, may be causing this? Some faulty temperature sensor that triggers the fan?

Asked on 6 July 2013 by SW, Liverpool

Answered by Honest John
I'd guess that the temp sensor/sender has stuck. This is a thermo switch screwed into the water jacket of the engine. In your case it seems to be stuck on.

Update: It later turned out to be a wiring fault.
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