Why does my sensor trigger without precipitation?
The precipitation sensor on a DS unit clears itself by evaporating the rain for snow that lands on it.
Over time, minerals and contaminants can be left behind by the evaporation process, thus making the sensor think that it still needs to be active.
It is recommended that the sensor grid be cleaned with water and a non-metallic (Scotch-Brite™ or equivalent) cleaning pad about every 4 months.