High Lockout
Fast Flashing (8Hz) on Glow-worm Micron 40FF

Your boiler has detected an internal electrical error or a component failure during its startup sequence that is preventing it from firing up.

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

Fast Flashing (8Hz)

What causes this fault?

This fault occurs when the boiler's internal computer performs a safety check during startup and detects a conflict between the fan and the air pressure sensor. The most common reason is that the control board is receiving incorrect electrical signals, or a vital component has physically failed and is preventing the ignition sequence from completing.

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.

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Related fault codes

Slow Flashing (2Hz)View →

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