There is a 'choke point' in the drain system.
If you remove the white nylon fitting on the left side you will see it.
It looks like a trap or siphon breaker with two large gray tubes and one smaller black one.
If you remove this part, examine it and clear it you can be sure the whole discharge tubing assembly isn't clogged.
In my case it only took two lemon seeds to stop the dishwasher with an OE error.
If you do replace the whole discharge piping assemble the problem will be solved (but only until it happens again).
C Affel