High Lockout
F70 on Glow-worm Ultracom 2 CXI

Your boiler's main control board has lost communication with its internal identity chip, effectively meaning the boiler has forgotten which model it is and cannot operate.

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

PCB personality chip fault

What causes this fault?

This fault occurs when the boiler's main control board loses its connection to the identity chip that tells it how to operate correctly. The most common reason is a hardware failure within the printed circuit board (PCB) or a loose connection to the data chip, often caused by age or electrical wear. In some cases, this can also happen after a replacement part has been installed but not correctly coded to the specific boiler model.

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

F61View →F62View →F63View →

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