Ok, i changed the sensor on the right of the cylinder head and all was well.
I now have the same fault flashing at me, the temperature gauge, with the ignition on and engine off is showing zero.
Start the engine and the guage immediatley goes to 100 degrees. and the cooling fans start.

The system senses voltage change I think. So I swapped back to the known dud one.
I got the flashing warning but the temperatue gauge did not move.
Went back to the other one and it was well for 30 seconds but then it flashed at me again.
One sensor has no reading across the pins, the other has a good reading. Using resistance.
It does this when run with the plug disconnected too so I have come to the conclusion there is somthing else a little wrong as well.

I do not have a big red flashing stop either. Perhaps the bulb has blown.
It seems to drive OK, I know the MAF has a fault, the accereration is not burning rubber but she is returning high 40's to 50 mpg.
Any Ideas.
its a 2001 110 HDI estate "Executive"