sounds like a code on a ideal isar or icos boiler? if so, the white plastic pipe from boiler has prob froze somewhere, does it go outside? if so pour hot water over the pipe to melt ice inside. but it could also mean other things im afraid, pcb fault, electrodes fault, and various other faults. if it is this boiler id advise getting engineer round if its not bn looked at for a while as these boilers need a safety upgrade due to a very poor burner insullation design, ive seen ones with holes burnt right through the back- crazy.
billy
December 2010