Hi Marc,

Had the same years ago. My sensor broke on the highway given a reading of 'hot' on my gauge. Went to the Ford garage and ordered a new one. Then my reading was as high as yours now. It seemed to be in the coloured ring of the sensor. Then vary from colour. If I recall correct original mine had a red ring and Ford delivered a sensor that looked like it, but that one didnt give the right output. The part came from their TIS sheets searching for a cosworth.
After going back they saw there was more than one option for the sensor. I ordered a new one with the same coloured ring as original and than the gauge read normal.

So no worries!