BoilerFaultCodesTechnical description
Primary water circulation fault
What causes this fault?
This fault occurs when the boiler detects that water is not moving quickly enough through the internal pipework to carry heat away, causing the system to protect itself from overheating. The most common reason is a failing internal pump that can no longer circulate the water, or a physical blockage caused by a build-up of debris and sludge within the system.
This issue often surfaces at the start of autumn when the heating is turned on for the first time after summer, as the pump can seize up during long periods of inactivity.
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 →