BoilerFaultCodesTechnical description
External heating program changeover applies to heating circuit without mixer
What causes this fault?
This fault occurs when an external control device, such as a smart thermostat or timer, sends a signal to change the heating program for a specific part of your system that isn't set up to understand that command. The most common reason is a configuration error in the boiler's software where it thinks it should be controlling a specialized mixing valve that doesn't actually exist. It can also be triggered by a loose wire or a faulty connection between your external room thermostat and the boiler's internal control board.
DIY fix possible
Check if any external smart thermostats or controllers have conflicting schedulesPress the 'Reset' button on the control panel to clear the temporary communication errorEnsure any external remote control apps are up to date