Diplomat Dishwasher E2 error code?

My Diplomat integrated dishwasher starts to work, you can hear the water going in, and then it beeps 4 times and stops. When you open the door it shows E2 as an error code and there is a pool of water in the bottom.
I have emptied the water and seen 3 holes in the lowest area, one has a rubber flap over it. I have tried soaking in bleach and adding boiling water, pushing things down the holes, plastic pipes and cleaning brushes; but they don't go far. I have blown water and air down the pipes, I have tried taking the dirty water pipe off and blowing down it....But all to no avail. It keeps doing the same things again. Mine doesn't have any lights, just 3 buttons (prog. time, eco) and power. Tried the reset...no help.
Any further ideas ?