OK, thanks for that.
Put the drain hose back into the stand pipe or onto the spigot it connects to.
The suds is a build up of soap and body fats in your machine.
These may be the cause of restrictions in the pressure system, causing the E20.
Basically, the machine empties (which is what I was trying to determine) then, after it's empty it comes up E20 because the pressure switch has been unable to reset quickly enough, due to restrictions.
If I'm correct in my assumptions, 2 or 3 boil washes with nothing in the machine should sort it out.
Connect it all up again, run it on it's hottest wash and let it go all the way through.
Repeat it twice more.
Hopefully, this will get rid of any soap build up and cure the problem you are having.
Try it out.
Get back to me if you find you need more help or there's further problems.
Hope this helps