Have had the same fault with our dishwasher. F4 is drain fault which could mean that there could be a partial blockage when the machine drains(pumps out).
Was instructed to remove bottom of pump to see if there was a blockage. But what I did was to connect the garden hose to the waste pipe. And slowly open the tap ( not fully) This did push back some debrie. Which I remove with a sponge. This did clear the fault.
shaun
February 2010