Your boiler has lost its flame while running and has shut down as a safety precaution because it cannot maintain a steady supply of gas or a spark.

Technical description

Flame failed during burner operation. Open the main shut off valve, shut down the appliance and check gas line, replace the ionisation electrode, set burner correctly and minimum rated load, check the integrity flue system and if the interconnected room air supply is too small, or the size of the ventilation opening is too small, clean the heating block on the flue gas side or replace the control unit/burner control unit