High Lockout
F61 on Ferroli BlueHelix Pro 25C

Your boiler's internal computer brain has detected a serious electronic failure and can no longer control the heating software correctly.

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) AGC01 error

What causes this fault?

This fault occurs when the boiler's main control board suffers a critical electronic failure, often caused by a power surge or localized component burnout. The most common reason is simply the natural degradation of the electrical circuits over time, which prevents the computer from executing the software needed to fire the boiler safely.

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

A62View →A63View →

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