High Lockout
17 on Glow-worm Xtramax HE

Your boiler is not receiving enough electrical power to operate safely, which is preventing it from heating your water.

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

NETWORK VOLTAGE TOO LOW: CHECK THE SAFETY ELECTRIC VALVE

What causes this fault?

This fault occurs when the electrical supply reaching the boiler's internal components drops below a safe working level. It is usually caused by an issue with the home's main power supply or a failing electronic part within the unit that can no longer process electricity correctly. Because the boiler cannot guarantee a safe ignition with such low power, it shuts down as a protective measure.

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

F15View →F16View →F18View →F19View →

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