High Lockout
F67 on Glow-worm Ultracom hxi

Your boiler's internal computer boards have stopped communicating correctly, meaning the system cannot process commands or operate 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 PCB / Display PCB fault

What causes this fault?

This fault occurs when the boiler's internal computer chips fail to recognize or communicate with each other, often due to a hardware malfunction or a breakdown in the electronic circuitry. The most common reason is a voltage surge or general component wear that scrambles the software, preventing the boiler from performing its safety checks.

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 →F64View →F65View →

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