Definitely one for a GasSafe/Corgi registered engineer!!
There are many possible reasons for this fault to occur.
It may well be part of a failsafe system that prevents the boiler from being lit if there's another problem.
Also you will be breaking the law by attempting to repair a gas appliance. By-passing safety components or any unauthorised repairs risk a gas explosion that could demolish a house!
OJ, August 2011
