BoilerFaultCodesTechnical description
Insufficient system water pressure
What causes this fault?
This fault occurs when the water pressure inside your heating system drops below the minimum level required for the boiler to fire up safely. The most common reasons are a leak somewhere in your radiator pipework or a faulty expansion vessel that is no longer able to maintain steady pressure as the water heats up.
This issue often appears when you turn your heating back on for the first time in autumn, as the system settles after being idle for several months.
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.
Find a Gas Safe engineer
Search the official register →