High Lockout
F17 on Glow-worm Xtramax HE

Your boiler is not receiving enough electrical power from your home's supply to operate safely and has shut down as a result.

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

Supply voltage too low (< 170V).

What causes this fault?

This fault occurs when the electrical supply entering the boiler drops below a safe threshold, meaning there isn't enough power to run the internal sensitive components. The most common reason is an issue with your home's incoming mains electricity or a failing internal circuit board that can no longer process the voltage correctly.

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.

Find a Gas Safe engineer
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Related fault codes

F11View →F26View →

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