I read this from this site.....

"Whenever my wif light comes on like that and there is no water (3 times so far in 145000 miles), I usually find the sensor is dirty. Before you replace the sensor, take a can of brake or carb cleaner (carb cleaner seems to work better) and heat the end of the little plastic straw and bend it 90* so there is about a 1/4 inch leg after the bend. Remove the drain plug, insert the straw and spray the cleaner around towards the front of the truck (where the wire harness plugs in to the cover).

I usually get a slimy brown or white goop to come out with the cleaner. Ill spray half the can around in there to be sure I got it all, then let it sit and drain for a while to get most of the cleaner out. After that the light stays out for a while. The first time I replaced the cover and saw the slimy stuff caked around the sensor. Since then I have just cleaned it with no problems. "

Sound plausiable?

Shane