High Lockout
F9 on Glow-worm Xtrafast 96

Your boiler has detected an issue with how it monitors water levels, meaning it cannot confirm there is enough water to safely provide heating or hot 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

Water pressure sensor fault

What causes this fault?

This fault occurs when the boiler's internal computer loses communication with the sensor that monitors water levels. The most common reason is that the sensor itself has failed due to age or internal corrosion, or the electrical wiring connecting it to the main control board has developed a loose connection.

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

F0View →

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