High Lockout
L9 on Ideal Logic Max Plus

Your boiler's internal computer has lost its settings or suffered a technical failure and can no longer control the heating 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

Printed circuit board (PCB) unconfigured or fault

What causes this fault?

This fault occurs when the boiler's main control board loses its identity or suffers an internal electronic failure, meaning it can no longer communicate with the rest of the components. The most common reason is a glitch in the software memory or a physical defect in the plug-in configuration chip that tells the board exactly which model of boiler it is controlling.

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

F7View →L2View →

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