High Lockout
LED 2 Fast Flashing (8Hz) on Glow-worm Micron 50FF

Your boiler has detected an internal electrical or computer error and has stopped working 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

Other Errors

What causes this fault?

This fault occurs when the boiler's central control unit suffers a critical communication failure or an internal electrical short. It usually means the main circuit board can no longer safely monitor the boiler's components, so it shuts down the system instantly to prevent damage. The most common reason is age-related wear on the control board's solder points or a surge in the electrical supply.

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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