I do not know the model for the error, but they use a level sensor same as on washing m/c's, which means it will be inside usually towards the top, a pipe and 2 wires will be connected to it, BUT rather than the switch itself being faulty, could be a blocked pipe. so look for a small 1/4" 5mm pipe coming from a larger plastic (funny shaped bottle type of thing) container, which could be on the outlet side, t'd off the main drain. Check the pipe is clear. If blocked the m/c would think it has water in all the time.
SD
January 2012