BoilerFaultCodesYour boiler is temporarily pausing to melt away ice build-up and protect the external components during very cold weather.
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: Defrosting
What causes this fault?
This occurs when the external temperature drops low enough for ice to form on the outdoor heat exchanger. The boiler temporarily reverses its operation to warm up these components and melt the frost to ensure airflow isn't blocked. Once the ice has cleared and the sensors detect a safe temperature, the unit will automatically resume its normal heating cycle.
This status is almost exclusively seen during the winter months when outdoor temperatures fall near or below freezing.
DIY fix possible
Wait for the defrost cycle to finish automatically (usually 10-15 minutes)Check that the external condensate pipe is not frozen or blocked with iceEnsure there is no snow or debris obstructing the boiler's external flue
Find a Gas Safe engineer
Search the official register for a qualified engineer in your area.
Gas Safe Register →Protect yourself from future repair bills
A boiler cover plan would cover faults like Flashing on and off — no call-out fees, no surprises.
Affiliate links — we may earn a commission at no extra cost to you.