Where is the 2005 Landyacht water tank sensor

Crawled all around under our new to us 2005 landyacht 30,looking for the MicroPulse sensor but don't even see the tank. Filler is drivers aft side, see the Grey and black water sensor but where the heck is the water one?

Also, how to get to the back of the monitor? Does the front pop off some how?

Sorry for the newbie questions, but thanks!!!