F4 means it's not drained, or registered the fact that it's drained in the allotted time. You can only check the obvious...clean the filter, then have a look in the sump area under the filter, there's a black plastic grid at the 3 o'clock position. Make sure it's clean...toothbrush and hot water etc but be careful not to poke anything sharp through the holes, there's a rubber diaphragm behind it which could get punctured.
If that doesn't sort it you may need an engineer to confirm a pcb fault
damion berridge, August 2007
