with the freezing weather condition lots of condensate pipes are freezing up this usual shows as an ignition fault, when you reset the boiler it will generally make strage shushing noises and lock out again.
1. trace the condensate pipe to the end this is likely to be where it is frozen.
2. use hot water,pour it over the pipe banging the pipe will loosen the ice.
as soon as the ice is gone water will run out of the pipe reset the boiler and do again the next day

darren, January 2010