Having read previous posts on this topic. (Start button flashes 4 times). Drainage problem.
I selected 70 deg (intensive) setting and ran machine. I opened door at intevals to check operation. Machine ran and filled with water ok. Base of machine covered by water. Checked base after approx 20mins and no sign of any water?
Machine ran for approx 30 mins in total and beeping re-occured. Pre-rinse LED on and start button flashing 4 times between pauses. Again no sign of water on base! Not sure why?
Apologies if this has been covered before but I am confused.
Take out the filters & look in the right hand side of the sump for one of these little chaps http://shop.ukwhitegoods.co.uk/Dish...%2526+Others+Dishwasher+Diaphragm+Switch.html Your pump may be functioning correctly but the pressure switch might be clogged or even defective. A common problem is that the grill gets gummed up with residue/bits of labels etc & the machine "thinks" it still has water in, hence the F4 alarm. Give it a good clean, or even better lie the dishwasher on its back & remove the bottom plate. This gives you access to most parts & the pressure switch is easily removed from underneath. Clean it well & if you have a multimeter check if it is switching ok by poking a cable tie or similar through the grill to activate the diaphragm.
I removed the pressure switch and disconnected the connector plug on wiring loom from same. On inspection part of the connector plug appeared to be "melted" (may have been a loose connection). Pressure switch contacts were also damaged and diaphragm was not switching when tested.
Fitted new pressure switch and connector. Ran to test. Perfect. Happy days.