High Lockout
F73 on Glow-worm Flexicom hx

Your boiler has stopped working because it cannot accurately measure the water pressure due to a sensor or wiring issue.

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

Pressure sensor fault

What causes this fault?

This fault occurs when the boiler's internal computer loses communication with the water pressure sensor, meaning it can no longer tell if there is enough water to operate safely. The most common reason is that the sensor itself has developed an electrical internal short or has become blocked by system debris, though it can also be caused by damaged or loose wiring between the sensor and the main control board.

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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