BoilerFaultCodesTechnical description
frost protection active (Priority 4)
What causes this fault?
This occurs when the internal sensors detect that the water temperature has dropped below a safe threshold, usually around 5°C. To protect itself, the boiler automatically fires up to circulate warm water and prevent the heat exchanger from cracking due to ice expansion. It is a normal safety function rather than a mechanical failure.
This status code is almost exclusively seen during winter or during sudden cold snaps when the ambient temperature in the garage, loft, or cupboard where the boiler is located drops significantly.
DIY fix possible
Wait for the boiler to complete its cycle; the code will disappear once the internal temperature rises above 7°C.Ensure the room where the boiler is located is slightly warmed.Check that your external condensate pipe has not frozen if the weather is extremely cold.