Technical description
Hot water demand via impeller sensor
What causes this fault?
This status code appears when you open a hot water tap, which triggers a small internal paddle wheel called an impeller to spin. This sensor tells the boiler's control board that there is a demand for hot water, prompted by the flow of water through the pipes. It is a normal part of the boiler's operation and simply confirms the system is responding to your request.
DIY fix possible
No action is required as this is a normal status message, not a fault code.If the code remains after you turn off your taps, check for any dripping or leaking hot water taps.Ensure your taps are fully closed to allow the boiler to return to central heating mode.