Join Date: Oct 2007
My Motorhome: Swift Kontiki 615
Thanked 870 Times in 782 Posts
Common problem as the gauges are often unreliable. If you have an access to the freshwater tank open it and have a look/feel of the electrodes in there - they may have calcareous deposits on them which can usually be cleaned off using a mildly abrasive scrubbing sponge (the ones with a white scrubber, not the more abrasive green ones) if that does not remove it, try wiping it over with a cloth soaked in vinegar (not malt vinegar as it is too strongly flavoured).
If those measures do not work it may be worth disconnecting the 12v supply and all connections to the control unit - so that resets the whole system. On our Sargent system that means removing it from the fascia and disconnecting the single plug and leave it out for 1 minute, that resets the whole lot on reconnecting.
If all of those measures fail, you may have to bite the bullet and either try a new sensor, or take it to an agent for checking.
Good luck, I hope that gives you some ideas, do let us know how things pan out, by the way, welcome to the forum.
Any typo that I make means the errorists win.
Any comments above are only MY OPINION
and should be read as that.