BoilerFaultCodesTechnical description
There is insufficient water in your system.
What causes this fault?
This fault occurs when the internal sensors detect that the water pressure has dropped below the minimum level required to protect the heat exchanger from overheating. The most common reason is a slow leak somewhere in your radiator network or a problem with the expansion vessel which helps manage pressure changes. In some cases, it may simply be that you have recently bled your radiators and haven't topped up the system water afterwards.
This fault is more common in autumn when homeowners turn their heating back on for the first time, as small leaks often develop while the system sits idle over summer.
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.