DANT-66

Hi I have a 2.2HDI mwb on an 05 plate and when starting from hot or cold the auxillary fan cuts in and runs for 5 mins or more which is very annoying as it puts van in a sort of limp home mode and also flicks on the engine warning light. Turning van off doesn't cut the fan out and only serves to run the battery down! Think its a faulty engine temp sensor but can anyone point me in the right direction to find the sensor. Have bought a replacement sensor but can't find the faulty sensor on the block! Any help much appreciated Cheers Dan