FANTASTIC!!! I must admit to being a little sceptical, but I figured I would take the plunge before shelling out £100 for an engineer. I did exactly as described and it was incredibly easy. The pump is secured by 3 star headed screws in my dishwasher (FDW80) but they are the only 3 screws that are accessable, so wasn't hard to figure. I found a small piece of plastic which had snapped off the cutlery tray....removed it, put everyhting back, and bingo! THANK YOU!!!
Disconnect the power supply, water & waste pipe. turn off the water, pull the dishwaher forward and lay on back, you will see two screws on the bottom of machine these are the ones that retain the leak sensor DO NOT REMOVE THEM you need to remove the plate that the leak sensor screws are on this can be done by removing the six small screws that are located each side (3 each side,) you can now remove the plate but be careful as the leak sensor is still attached there is plenty of slack in the wiring to allow you to place the plate to one side.
Follow the pipework that comes from the water waste bowl that goes into the small pump (pump not as big as you expect) the pump is held in place by 3 screws remove the 3 retaining screws clean pump I found a tiny piece of bone that had stopped the pump impellor from draining the machine causing the AL03 error. This will save you the cost of engineer for 30mins investigation good luck.