Re: 2009-2900 mk
When you travel, leave about 5-6 gallons of water in all the tank. Put calgon and Dawn dish soap in all of them. The sloshing action will help keep the sensors clean. If you dont have one....get a clear plastic connector for your drain pipe. You will know when the tank is clean and empty.
BTW, most sensors are very unreliable. Been that way for the 40 years we have had RV's.