temp gauge and red light problem

[stevieee]

Hi,
can anybody help me out with a problem I'm having with my T25 diesel.
as soon as you start the engine cold the temp gauge rises right up to the top and the red light stays flashing.
i have changed the temp sensor on the head and check water pipes and the filler cap are all working and no leaks.
have i missed something silly?
it did it about 6 months ago but only for about 10 mins then went down and light went out. but has now started doing it again
cheers
Steve

[Grun]

Most probably a short circuit in the yellow/red wire from the multipin connector to the temperature sensor,Insulation cracked,worn,burned... or possibly on the pcb behind the instruments. Waterboxer system below...... diesel should be very similar.

Diagram courtesy of AngeloEvs.
Mike