I had this problem and found the plastic tray underneath the dishwasher was filling up with water which made it think there was a flood.
For may months I just used a Vacs wet hoover every couple of weeks with a 6mm plastic hose taped to the nozzle which I inserted under the bottom of the door when it is open and sucked the water out of the plastic tray.
You need a torch and have to remove the lower small white panel beneath the door.
Best to turn off the mains also.
It turned out the water was getting past the door seal I think and this was eventually sorted when the salt dispenser packed up and a service engineer replace some bits.
D Graham
November 2005