BoilerFaultCodesTechnical description
The boiler shuts off automatically. The minimum permissible level for the safe and efficient operation of the appliance is 0.5 BAR.
What causes this fault?
This fault occurs when the water volume inside your central heating system drops below a safe operating level, often due to a small leak in the pipework or a radiator. It can also happen if your radiators were recently bled without the system being topped up, or if an internal component like the expansion vessel is no longer holding pressure correctly. When the pressure drops too low, the boiler shuts down to prevent the internal heat exchanger from overheating and sustaining permanent damage.
This issue is more common at the start of autumn when homeowners turn their heating back on after a long summer break, often revealing small leaks that developed while the system was idle.
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.