BoilerFaultCodesYour boiler is not broken; it has simply noticed the temperature is very low and is running briefly to prevent the internal pipes 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 active (Priority 4)
What causes this fault?
This status occurs when the temperature sensor inside the boiler detects that the water has dropped below a certain threshold, typically around 5°C. To prevent the heat exchanger from cracking due to ice, the boiler automatically fires the burner to gently warm the internal components. It is a safety feature designed to protect your heating system during periods of extreme cold.
This code will almost exclusively appear during the winter months when outdoor temperatures drop near or below freezing.
DIY fix possible
No action is required as this is a normal safety function.Ensure your thermostat is turned up if you want the heating to stay on.Check that any visible external pipes are properly insulated to prevent freezing.
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A boiler cover plan would cover faults like S.34 — no call-out fees, no surprises.
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