BoilerFaultCodesTechnical description
External controls heat demand
What causes this fault?
This code appears when your external thermostat or smart control system sends a signal to the boiler asking it to provide heat. It is not a breakdown, but rather a normal status message confirming that the boiler has received the command and is currently working to warm your home. If your radiators are not getting hot while this is displayed, the issue likely lies with a pump or a zone valve rather than the boiler itself.
This code is most frequently seen during the autumn and winter months when heating demands are high and the thermostat is active.
DIY fix possible
Check your room thermostat or timer settings to see if you are calling for heat.Lower the temperature on your thermostat to see if the code disappears.No action is required if your heating is currently turning on and off when you expect it to.