High Lockout
13 on Glow-worm Ci Plus

Your boiler's internal computer has encountered a critical error and can no longer communicate with the rest of the system.

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 unit suffers an internal electrical failure or a memory corruption. The most common reason is age-related wear on the electronic components, though it can also be triggered by a sudden power surge or moisture getting onto the circuit board.

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

12View →14View →F1View →F13View →

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