BoilerFaultCodesTechnical description
The water pressure falls below 0.3 bar. The unit switches off. Fill the system up with water before you start up the appliance again.
What causes this fault?
This fault occurs when the internal water pressure drops so low that the boiler can no longer safely transfer heat from the burner to the water. The most common reasons are a slow leak hidden somewhere in your pipework or radiators, or the pressure being accidentally released through a safety valve.
This fault is frequently seen in autumn when homeowners turn their central heating back on for the first time, as the sudden heat can expose small leaks or issues with the expansion vessel.
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.