Just had F-12 on my Hotpoint Aquarius washing machine (don't know model off the top of my head). Problem was due to water not draining. Power off. My machine has access plate at bottom on the back. The water drain is held onto the drum via a jubilee clip and when i took it off the drain was clogged with hair, sweet wrappers, money, hair bobbles and a nintendo computer game !! Once cleared, put back as was - machine now running ok.
Richard Collett, May 2008