Originally Posted by Pastordick
Gray water holding tank level sensors have gone bananas. Never shows less than 1/3 and now shows F when I just emptied the tank
I'm not really sure how these things work, but I think they can somehow get jammed by crud in the tank.
Other than that, I guess that it is an electrical problem
I remember seeing somewhere that you could buy a liquid to put in the tank to "clean" the sensors -- or maybe I dreamed that
Any help from anyone?
You don't specify what your rig is, but I had the same problem with my gray tank. It has the thru wall sensors that read through the plastic and don't penetrate. Some others use the kind that go into the tank through hole in the side.
I installed one of the Tornado turbo washer systems and when I drilled a hole to install it, there was a 1/16" thick coating of grease and scum on the inside of the tank. That was preventing the sensor from reading the liquid level. The sensors that penetrate can also get coated with scum.
Several sessions of a half full tank with a little Dawn dish soap sloshing around and the turbo washer cleaned it up and the sensors work fine now. I just make sure to rinse out for a minute after every gray water dump to keep the inside clean. Don't use too much dish soap or you will get a LOT of suds, trust me.