I had the same issue with lights 4 and 5 flashing and the dishwasher would not drain. After doing all the obvious things, cleaning the filter etc. I took the dishwasher out and placed on its side. Undid the 6 screws, three front three back of the bottom plate. You can then see the pump where the outlet hose is attached. I undid the one screw holding the top part of the pump, took the drain hose off the pump so I could twist and remove the top half of the pump. Then by using a screwdriver I tried to move the pump rotas which were jammed with small blue plastic parts from the cutlery basket which has started to break up. Ones removed and the rotas were moving freely I reassembled and all is now working great again.
Terry Edwards, January 2013