After fitting a new censor on the engine block the problem still persists. The temperature gauge keeps rapidly moving into the red zone resulting in the alarm going off.It then it fluctuates rapidly up and down.
Hope this information helps you in diagnosing this problem.
There are no signs of overheat as sometimes you can drive for 30 miles or more before the problem shows. The cooling fan appears to function as it should although I have not checked the actual temperature of the cooling system.