very often with these units the watervalve has failed ( slightly ) ... it is allowing water in the tank even though the d/w is not on... water has filled the tank and gotten down into the bottom environment where the styro float mechanism trips a micro switch ... need to disconnect power and remove the water from that basin area in the white plastic environment ( where float is as well as where the circ pump is too.. ) shut water off to d/w and replace inlet valve.. more than likely the inlet valve is your problem ( MIGHT be a leak with circ pump, but unlikely ... )