BoilerFaultCodesYour boiler has detected that its internal temperature is too cold and is running specifically to prevent itself from freezing.
This is a minor fault. Keep an eye on it and mention it at your next annual boiler service. Reset the boiler and see if it clears.
Technical description: Frost protection: heating the exchanger (if the heat exchanger temperature falls too low, the burner switches on and the external pump runs until the temperature is sufficient).
What causes this fault?
This code appears when the water temperature inside your boiler's heat exchanger drops to a level where it is at risk of freezing. To protect itself from damage, the boiler automatically fires the burner and starts the pump to circulate warm water until a safe internal temperature is reached. This is a normal safety function rather than a mechanical failure.
This code is almost exclusively seen during the winter months when external temperatures drop near or below freezing.
DIY fix possible
Ensure the gas supply is onCheck that any external frost thermostats or TRVs are openWait for the boiler to finish its warming cycle and the code will disappear automatically
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