Hi Kevin. There are multiple reasons these do not work. If you do a search of this web site you will see many posts with a similar problem and ways to try and fix it. The sensors are the same type that are used in the RV industry. I have owned almost a dozen different rv’s with this system and not one of them worked accurately for more than (the warranty period) a year or so. It is a weak and sensitive system that fails often. In FM’s defense it is the only reasonably priced system available to date so that is what they, and most others, use. Unfortunately I am batting 1000, mine has never worked correctly since we bought our boat. We’ve learned to estimate the level pretty accurately and just live with it. Good luck and keep us posted on the final outcome.