High Lockout
F12 on Glow-worm Ci Plus

Your boiler’s internal control screen and main computer board have lost connection with each other, preventing the boiler from functioning.

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 / Main PCB communication fault

What causes this fault?

This fault occurs when the digital communication between the display panel you interact with and the boiler's internal computer breaks down. The most common reasons are a loose or corroded wiring connection between the two components, or a hardware failure on one of the circuit boards caused by age or power surges.

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

F11View →F13View →

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