I had the same problem on Whirlpool AWO 3555, it kept saying FP and -p-. I had an error before where it flooded the room, it was the filter in front which had a string from some trousers in it. This time, the filter was clean, so I searched the internet and found this page.
Once I de-attached the pump, I found a sock sticking out of the hole in the washing machine.
I had a few problems attaching the thingy clip again, around the tube - since it takes alot of hand powers, but a set of plyers did the trick!
So for the females, we can do it too! ;)
Regars from Sussi in Denmark :)
Sussi
August 2010