High Lockout
15 on Glow-worm EnergySaver Combi

Your boiler's main internal computer has encountered a critical error and is unable to operate the system safely.

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

There is an internal fault in the Automatic Control Module.

What causes this fault?

This fault occurs when the boiler's central control unit suffers an internal electronic failure, meaning it can no longer safely monitor or manage the heating process. It is often caused by damaged circuitry or a component failure within the module itself, which prevents the boiler from communicating with sensors and valves. Essentially, the boiler's 'brain' has stopped working correctly, and it shuts down to prevent any unsafe operation.

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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