The dishwasher does drain but not fully and leaves 1-2 inches of water after a cycle.

I've checked all the filters and cleaned them out (they certainly weren't blocked), removed the drain hose and run water through it (even backflushed it), checked the flapper valve, checked the P-trap etc. etc..

The dishwasher does drain, I've run it and just put the hose into the sink and can see it draining. The water doesn't fly out of the drain hose like a hosepipe though. And there is always water left at the bottom after a cycle.

How does the pump work? Does it just run for a set time and then cut out or is there a sensor which tells it when to switch off as should be empty?

I'm a little stuck at the moment as everything seems to be working (pump etc.) other than the 1-2 inches of water after a cycle.