High Lockout
41 on Glow-worm EnergySaver Combi

Your boiler's internal computer has developed a fault and can no longer communicate with the rest of the system safely.

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

There is an internal fault in the Automatic Control Module.

What causes this fault?

This fault occurs when the boiler's main control board experiences an internal electronic failure or a breakdown in its memory processing. It is usually caused by aging electrical components on the circuit board that have finally worn out or been damaged by a sudden power surge. Because the 'brain' of the boiler can no longer verify that it is operating safely, it shut downs the system entirely to prevent any hazards.

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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