BoilerFaultCodesTechnical description
Indicated if the red arrow on the system pressure gauge is set above zero and the system pressure is seen to fall below this value over a period of time, indicating a water leak.
What causes this fault?
This fault occurs when the sealed system no longer has enough water to circulate heat safely, triggered by a physical escape of water from the pipework or components. The most common reasons are a weeping connection on a radiator valve or a internal part like the expansion vessel failing, which forces water out through the safety discharge pipe.
This issue often comes to light in autumn when the heating is first turned on, as the increased heat and pressure stress seals that may have perished over the 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.