High
F0 on Glow-worm Xtrafast 96 120

Your boiler has stopped working because the water pressure is too low for the system to run safely.

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.

What the manual says

Manufacturer manual

Insufficient water pressure in the system (less than 0.5 bar)

From this model's manual
Verified against the Glow Worm Xtrafast 96 120 installation & service manual.
Plain-English guidance below. Severity, DIY steps, costs and parts are our interpretation to help you act, not text from the manual.

What causes this fault?

This fault occurs when the water level inside your central heating system drops too low for the boiler to operate safely. The most common reasons are a slow leak from a radiator valve or pipework, or the air being manually bled from radiators without the pressure being topped back up.

This code is particularly common in autumn when homeowners first turn their heating back on after summer, causing old seals to weep or revealing pressures that have slowly dropped during months of inactivity.

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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