High Lockout
F9 on Ideal Logic+ Heat

Your boiler’s internal computer brain hasn't been programmed correctly, meaning it doesn't know which model it is and cannot start up.

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

Unconfigured printed circuit board (PCB)

What causes this fault?

This fault occurs when the boiler's main control board has lost its identity or was never properly told which model it is installed in. It usually happens after a power surge scrambles the memory or if a new part was installed without the specific configuration chip being inserted. Without this digital profile, the boiler cannot safely coordinate the fan and gas valve, so it shuts down as a precaution.

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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