i have a hotpoint ultima ctd80 which i have had the last 2 years, it has shown error codes f11, f10 and f15, every time i fix this problem by first switching off and unplugging appliance then removing small cover from back (middle with 2 screws) then larger panel that the smaller panel overlapped. once you remove these you will see the heating elements, remove the 2 screws at the back off this, remove cover carefully then at the top you will see two things (not very technical lol i am a woman), with a pin press the pin in the one with a hole, mine makes a clicking sound when i do it, not sure if it meant to but works for me. put all parts back together and thats the job done. make sure both fillters and water emptied regular, hope this helps and saves you a fortune on call outs
buddha, January 2009