Your boiler is struggling to keep its burner lit and has shut down for safety after failing to detect a steady flame several times.

Technical description

Flame lost signal lost 5 times in 4 minutes. Flame sensing error. Failing gas pressures. Fan fault. Flue blockage. Check flame detection lead between sensor and ignition control board. Check the gas supply, does pressure fall when burner fires? Check that flue system is not blocked.