The forums indicate that one solution for this problem is replacement of the sensor assembly, which is what I did. Upon switching the sensor assembly it DID work for one bucket full, but then went back to indicating bucket full when it isn't. Other fixes indicate changing the switch assembly, which I tried to do but the part has been discontinued. The only other item is replacement of the main computer, which the cost added to the cost of the sensor assembly would equal the cost of replacement of the appliance, so I won't go there.
Googled message to see that it was probably the sensor or the bucket full button. The bucket button is no longer made, but the sensor was available, so I gambled and bought it to try. We removed the outer housing and old sensor. then replaced new sensor putting it in same place and following the path of the old one to plug in wires. the whole housing had to be removed, could not just remove a section. Once replaced, plugged in to test, seemed to work. so replaced all the housing and screws. Unit is working again. Definitely worth the gamble, bc a tech would have been 3-4 times more expensive. My tenant was also confidant about being able to replace the sensor. After we did it, I think I could have done it too.