High Lockout
F12 on Glow-worm Xtramax HE

Your boiler's main control board has lost connection with the display screen, meaning the system cannot receive instructions and has stopped working.

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

User interface (display) communication error.

What causes this fault?

This fault occurs when the digital conversation between the boiler's internal computer and the front display screen is interrupted. It is usually caused by a loose wiring connection or a component failure on one of the circuit boards, preventing the boiler from receiving your temperature settings.

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

F13View →

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