Your boiler has detected a communication problem with the pump that circulates hot water around your taps, which may cause delays in getting hot water or stop it altogether.

What causes this fault?

This fault occurs when the boiler's control board loses its connection with the pump responsible for moving hot water to your taps. It is usually caused by a failure in the internal electronic expansion module or a loose connection in the wiring harness that bridges these components. In some cases, the pump itself may have developed an electrical fault, preventing it from reporting its status back to the main system.