flashing header tank empty guage

[g858]

Hi all,
Time to test your knowledge!!

I've got a MK2 1800 8V which a warning light keeps flashing on the dash. Its the one which signifies that the header water tank is low. I've check this and its not,  its up to the max. Checked the connections and all seem ok. Wiggled wires and other sensors but no joy. Everything else seems to be working fine ie fan, thermostat etc.
Any ideas what might be wrong, as i've got a long trip soon and don't want any hassle.
Any help would be much appreciated.

Cheers

[Dizzie]

is it leaking at all? anywhere on the system, not just the tank.

[Gambit]

replace the sensor or check the earths, only about a ?5 or something from EuroCarParts

[g858]

is it leaking at all? anywhere on the system, not just the tank.

I think it maybe leaking a tiny bit, but hardly any. Not enough to worry about i don't think, but i'm no expert!!

[g858]

replace the sensor or check the earths, only about a ?5 or something from EuroCarParts

Is it simply an expansion tank sensor i would need then, or something else?

[...joe]

when you check the water level is the car up to temperature? if so check it when its cold and see what level its at. they work on a pressure system and when hot the water level rises so would give you an inaccurate reading. test it cold and add antifreeze/water if needed and see if that makes any difference.