how to fix Diplomat model ABA 9242 Integral dishwasher?

Diplomat model ABA 9242 Integral dishwasher. starts programee ( i.e 1 Rinse ) pump runs to drain water then changes to draw water in through inlet hose. Stops & bleeps ( 1 beep every 30 sec's) Upon opening door, about 1 " of water is in the bottom tray & illuminated indicator ( on top side of door ) Flashing
E 4. No leaks, & all electrical wiring seems intact ??