BoilerFaultCodesTechnical description
Insufficient system water pressure (min. 0.5 bar) prevents the pump and fan from operating.
What causes this fault?
This fault occurs when the water level inside your central heating system drops below the minimum required for the boiler to operate. The most common reasons are a slow leak from a radiator valve or pipework, or the air pressure inside the expansion vessel needs recharging. In some cases, it can also happen after you have recently bled your radiators, which removes air but also lowers the overall system pressure.
This issue is frequently seen in autumn when homeowners turn their heating back on for the first time after summer, revealing pressure drops that occurred 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.