Vauxhall Vectra Coolant Temperature Sensor

I Notice That The Fan Does Not Work When The Engine Is Hot Which Cause My Engine To Overheat, So I Replaced The Sensor And After Three Weeks...

Hi My Vectra Is A 2.0 Dti Is Using Alot Of Diesel Im Only Getting About 35 To A Gallon , Have Changed Stat And Coolant Temp Sender And Had...