what is an F2 error on glow-worm 30ci?

my glow worm 30ci was working fine until a week ago, i noticed that the radiators were cold, checked the boiler and the indicator light was flashing red and the display read F2. this error code is not in the manual, i have emailed glow worm but so far they have not bothered to respond! I have had no hot water or heating for a week and i don't just want to replace the boiler if it isn't necessary. can anybody please tell me what this code means? :)