BoilerFaultCodesTechnical description
The appliance has a built in frost protection circuit. Should the Boiler temperature sensed at the primary thermistor fall below 5°C the Boiler will operate in central heating mode and continue to operate until the primary thermistor reaches approximately 30°C.
What causes this fault?
This code occurs when the water temperature inside the boiler drops to a critically low level, usually due to the heating being turned off during very cold weather. The system detects the risk of ice forming and automatically fires the burner to gently warm the internal components. This is a safety feature designed to prevent the heat exchanger from cracking due to freezing.
This display code is only seen during the winter months or during periods of extreme freezing temperatures.
DIY fix possible
No action is required; the boiler is performing a self-protection function.Ensure your gas and electricity remain switched on during cold weather.If the boiler is in a cold location like a garage, check that the area is well-insulated.