I wrote this blog article because I just couldn't find any information online about to resolve the above issue and hopefully it will save you some time.

Yesterday the drainage pipe on my washing machine came loose and the eventing water works filled the kitchen floor with water as I pulled the dishwasher out to hurriedly get to the washing machine pipe. After mopping up the floor and later that evening putting the dishwasher on, the dishwasher began to constantly beep/buzz and the Express wash light continually flashed. After some searching I eventually managed to get hold of the service manual (not the users manual) for the dishwasher.

It appeared this particular warning is error code 4 which indicates an "Overflow failure". The dishwasher beeps for 30 seconds and then constantly tries to drain water. The thing was there was no water in the dishwasher! However I did click that this may have had something to do with the washing machine flooding the kitchen earlier. Looking around the dishwasher I tilted it up on one side off the floor and as I did water poured out of a small hole onto the floor for a little while. I then tilted the other side of the dish washer over and more water leaked out over the floor for a little while. I then turned the dishwasher back on and hey presto it worked!

The dishwasher obviously thought it was filled with water. However the water couldn't be drained as it wasn't really inside the wash area.

Anyway hope this helps someone