BoilerFaultCodesTechnical description
Frost protection mode
What causes this fault?
This occurs when the sensors inside your boiler detect that the water temperature has dropped near freezing levels, usually below 5°C. 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 most common during extreme winter cold spells, particularly if the boiler is located in an unheated area like a garage or loft.
DIY fix possible
Wait for the boiler to finish its defrost cycle automaticallyEnsure the room thermostat is turned up to a normal heating temperatureCheck that any external condensate pipes are not frozen or blocked
Find a Gas Safe engineer
Search the official register →