water temperature gauge dips severely on acceleration?

[Editor]

Hiya-sorry if this has been done before-I did have a quick search.

Now then, my water temp gauge sometimes does some odd things. Like sometimes it's inert,& then boing, it springs up & registers in the middle where it should be. This is from start, it's never done this whilst driving. What it DOES do is dip down, almost to the bottom, if I boot the car hard, & then it then climbs back up to a bit below the centre.

Coolant level fine. We do occasionally have the STOP, engine temp too high on start up sometimes though. I've seen the thread & how-to on that-cheers Leghorn.

Any thoughts? With the rep for pug electrics I'm suspecting some kind of dodgy connection/sensor rather than the cooling sytem being at fault, but what do I know?

[jasper5]

I had a similar fault on my 406 HDi 90, the problem turned out to be the engine management coolant sensor.

On my 90 it is fitted into the cylinder head behind the air filter housing, it has a green electrical connector, the sensor itself is green, it is held in by an omega shaped metal clip.

The symptoms were high temperate fluctuating between low and high, with the STOP light coming on without any sign of overheating, ie, water loss.