the water pressure switch on this boiler has a nasty tendency to clog up which would stop boiler firing
is LED 5 flashing? [low water pressure]
but pressure gauge reads ok?
if your confident enough its possible to clear blockage on water pressure sensor provided you follow the boiler manual instructions for removal of WPS to the letter
involves draining boiler,electrically isolating, breaking water connections, cleaning defective parts, refitting, repressurizing, testing for leaks, power on, checking boiler works
if any of this frightens you
best get professional help
manwithnoname
May 2011