BoilerFaultCodesTechnical description
Heating mode error – water pump running
What causes this fault?
Strictly speaking, this is a status message rather than a mechanical failure, indicating that the boiler is in a pre-heating phase. It occurs when the control system has told the pump to move water throughout the radiators, but the burner hasn't actually switched on yet. This often happens if an external thermostat is calling for heat or if the system is simply performing a routine check before ignition.
This code is most frequently seen in the autumn when homeowners first turn their heating back on after the summer and the system takes a moment to prime itself.
DIY fix possible
Check that your room thermostat or programmer is set to a high enough temperature to trigger heatEnsure all radiator valves are openWait up to 10 minutes to see if the code changes to a 'running' status (S.04)