Tic, your sensor is probably a Catcon threaded near the bottom of the tank wall nearest center-coach, or perhaps a side wall. I hear it can be no picnic to get to, but then I've never tried - on our era coaches it may be no problem. Catcons use telephone-type wires/connectors, and it may have come askew or become dirt-fouled. Just use proper safety measures to support the coach before crawling underneath.
Also check the club's Coach Assist section here where there are 3 documents related to Aladdin. One for trouble-shooting is not in alphabetical order like it should be, so scroll down a ways to locate it, and check page 18.
Home tab at top of this page > Private BAC Members Only > Link to Coach Assist: Owners and Equipment Manuals > click on the link in Tim's message.
I've had my other tanks read more than 100% because they have no overflow valve, and can have excess fluid weight in piping above. Catcons work by sending electric current that's relevant to the pressure of the weight of fluid above them to the Aladdin module. The water tank has an overflow valve that should prevent the backup of water beyond the full tank calibration. Even if it were blocked somehow, you likely couldn't get 20% more in via piping. So check the connections at the tank and modules, and consider going through the recalibration procedure. Worse case scenario is the Catcon needs replacement; BCS did my black tank last fall and it seemed like a simple-enough procedure - I think they just unscrew from the tank body; but water tank sensors aren't exposed to fouling, so I'd not expect changeout to be a common necessity there.
-Joel
