High Lockout
13 on Glow-worm Ci Range

Your boiler's internal computer has developed a fault and can no longer control the heating and hot water functions 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

Main board fault

What causes this fault?

This fault occurs when the boiler's central control board suffers an internal electronic failure, preventing it from processing data or sending signals to key components. The most common reasons include a sudden electrical power surge, moisture getting onto the circuitry, or general component wear and tear over many years of use.

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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