there is a thermal fuse (144c )situated at the back of the fan oven , to access this you remove the panel with the incoming mains connection on it atthe back . i cannot say what causes this to blow other than its got too hot outside the oven which could mean the fan has failed but until you replace it you will not be able to tell . this could mean your controller is fine and replacement fuses would be pence from somewhere like rs or farnells .
mark dawson, November 2008