BoilerFaultCodesTechnical description
Water pump return water
What causes this fault?
This fault occurs when the boiler's sensors detect that water is returning to the unit too quickly without losing heat, which usually means the water isn't circulating through your radiators properly. The most common reason is that the valves on your radiators are closed or there is a physical blockage in the pipework preventing the flow. It can also be triggered if the boiler's internal pump is struggling to push water around the system.
This code often appears at the end of autumn when heating systems are switched back on after being idle for several months, which can cause internal parts or valves to seize up.
DIY fix possible
Check that at least two or three radiator valves (TRVs) are fully open to allow water flow.Ensure the external heating bypass valve, if visible, is not completely shut.Gently bleed your radiators to ensure there is no trapped air causing a blockage.