BoilerFaultCodesTechnical description
Target value for ext. controller lower than 20°C: Reference setting for continuous controller 7-8-9 or eBUS controller is <20°C and blocks the heating mode
What causes this fault?
This status occurs when the external thermostat is telling the boiler that the house is already warm enough, so the heating remains off. The boiler is physically capable of firing, but it is currently being 'blocked' or held in standby by the settings on your wall controller or smart app. This typically happens if the target temperature is set lower than the actual room temperature or if the thermostat batteries have failed.
This code is very common during spring and autumn when outdoor temperatures fluctuate, causing the thermostat to frequently reach its target and shut the heating down.
DIY fix possible
Check your wall thermostat or room controllerIncrease the temperature setting to above 20°CEnsure the thermostat is turned on and has working batteries