An FL on a Kenmore Elite Oasis washer indicates that an analog water level pressure sensor signal is out of range. The analog pressure sensor is a component on the machine control board. This could be caused by a problem with the air pressure hose connection between the bottom of the washer tub and the machine control board. The first image below shows how to access this air tube on a typical Oasis washer. If you have this type of washer, you can unplug the washer and check this air tube. The second image shows how to access the machine control board so that you can check the air hose connection to the analog pressure sensor that is on the machine control board. If you find no problems with the air hose and its connections, then the machine control board would need to be replaced.
If you need parts, you can order them from the Sears PartsDirect website.