(T) fiat ducato motorhome 2.8jtd 2003/4

The water temperature gauge has been mis-reading. Sometimes the gauge goes to the 9 o'clock position as soon as the ignition is switched on. After driving for some time it goes almost to the top of the gauge. Recently it has been going into the danger zone and the red over heating warning light has come on. If you stop for 10 mins the light goes off and the gauge drops to just below the top of the gauge. I can then drive 30-40 miles before the gauge goes to the overheat position and red light comes on. Again if you stop for about 10 mins the light goes out and you can start again. The local mechanic has checked that the thermostat and cooling fans are working correctly and also says the engine is not overheating. I have looked back on this site but could not find mention of the red warning light coming on with the mis-reading gauge. Help please.

If you're absolutely sure the engine is not overheating then the obvious culprit would be the temperature sensor.

same thing happened to me in France. I have a Fiat 2.8JTD. the mechanic changed the water temperature gauge and everything was fine then. Cost approx 50 euros - that was 3 years ago.

Ian