E20 is an error code for drainage failure.
Check where the appliance drain hose connects to the house drains for a blockage.
If it's onto a spigot under the sink, take them off and check both for a blockage.
If these are ok then it's likely to be a blockage in the pump.
You'll need to drain the water out manually.
Put a shallow dish below the filter and slacken the filter.
Tighten it to stop the flow of water while you empty the dish.
Once empty, take the filter out, clean out the debris and ensure nothing is left jamming the pump.
Before refitting the filter, put the machine on drain or spin and listen at the filter housing to see if you can hear or see the pump running.
If you do, fit the filter and try the machine again.
If the pump isn't running then something is jamming the impeller,or the pump isn't getting the required voltage ;or it has failed.
paul, March 2012