Grey tank sensor malfunction

[ABQTiger]

We have a 2020 Newmar Dutch Star. The Black tank volume indicator works well, but the grey tank indicator stays at 65 or 70%. We let it fill the last trip and it registered 90%. When dumped it went back to 70%. When we got home it read 10% briefly then went back to 70%. Ideas? Suggestions? We are still motorhome newbes.

[Dval]

Only a guess but it could be build up of grease on the walls of the tank or a bad sensor try filling to 80% ad dishwasher liquid soap and take a ride dump gray tank and see if that helps. Good luck .

[SKP Kirk]

Agree that it is likely a buildup on the walls of the tank. Most standard tank level indicators just have a series of buttons in the tank wall and when current passes between them it shows the level. It is quite normal for those to indicate more than is really the tanks soon after you start using it. Most likely it won't be long until the black tank level sensors start to do the same.