BoilerFaultCodesTechnical description
Internal boiler error (usually air in system)
What causes this fault?
This fault occurs when the water inside your boiler heats up too quickly because it isn't moving through the system as it should. The most common reason is trapped air pockets that block the flow, but it can also be caused by a buildup of sludge or a failing pump that is struggling to push water around.
This issue often appears in autumn when the heating is turned back on for the first time, as air can settle in the pipes or pumps can seize during the summer 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 →