Has any one had or have this problem,start up and drive away after a few mins temp gauge starts reading up to temp ok,
then not always but when driving along the gauge drops to bottom and stays there for different lengths of time then comes back up to norm.This might only happen once in a journey or several thins and even not at all no set pattern to it, could it be the engine temp transmitter if so where is it any clues

I have now cured this problem it was down to of all things the oil temp sensor in the sump,it seems all this lot is linked together for all sorts of reasons ie cold/hot starting even something about auto gearbox changes when cold or hot

Thanks for posting the fix. Always interesting to hear of a problem solved. Was under the impression that a faulty oil temp sensor would give you an unstable idling speed though.

I have a weird fault where the torque converter momentarily unlocks just as the engine hits full operating temperature and then again about every 20 minutes or so. I have changed the oil temp sensor and have considered changing the water temp sensor because as you say they do work together and affect the transmission behaviour too. 2008 MY Java Black TDV8 HSE