I do not know this boiler but pilot lights have a safety feature to do with flame failure - should the gas supply be interrupted - in case the supply returns without the pilot there would be an explosion!
To guard against this happening there will be a flame-failure device - to detect the heat from the pilot flame.
Your flame failure system is defective. Maybe the electronics that control it - maybe the flame is weak - maybe the sensor is in the wrong place in relation to the flame - or just not working.
These are all just guesses
Good Luck..., May 2016
