High Lockout
F16 on Glow-worm 30ci Plus

Your boiler is failing to detect a flame when it tries to fire up, so it has shut down for safety.

Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed

Call an engineer soon

Book a Gas Safe engineer within 24 to 48 hours. Your boiler may be unsafe or could break down completely if left.

Technical description

Flame detection fault

What causes this fault?

This fault occurs when the boiler's control system cannot confirm that a flame has successfully lit within the combustion chamber. The most common reasons are a worn-out sensor that can no longer 'see' the flame or a fault within the internal electronics that prevents the signal from reaching the main control board.

Engineer required

This is a high severity fault. Stop using the boiler and call a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.

Find a Gas Safe engineer
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Related fault codes

F1View →F4View →F14View →

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