i Have Diplomat dishwasher ?

Hi Graham, you do not specify what model you have as Diplomat is only the MFI code and these were made by 3 to 4 different manufacturers. I think you may have an ADP8322 variant.F8 on this means a water level failurer.It tells me on my list the following:
Water inlet defective should cut in after 1 litre
Sieve(filter) blocked
Water is foaming too much
A pot has turned over and filled with wash water.
No stable spray pump pressure.
Look at the grey tube that connects the filter to the top arms.That comes loose and it looses pressure.
Hope this helps, All the best.

FOXY
September 2008