BoilerFaultCodesTechnical description
Primary circulation fault
What causes this fault?
This fault occurs when the boiler detects that water is not moving through the internal pipework fast enough to carry heat away from the burner. The most common reasons are a failed internal pump that can no longer push the water, or a blockage caused by a build-up of debris and sludge within the system. Because the water stays still and overheats rapidly, the boiler shuts down to prevent damage to the heat exchanger.
This issue is most frequently seen during the first few cold days of autumn when the heating is turned back on after being idle all summer, which can cause internal pump parts to seize.
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.