2006 issue with engine cooling fan staying on

[garden guru]

Hi

I have now got a problem with cooling fan staying on even after ignition is off and keys gone. The only way I can stop it is to disconect the wire connectors.
Any clues please? It had a new radiator and stat and water pump last year. Are there any sensors or relays I should check? please give me as much detail as possible as I am learning just now.

Thanks
iain