BoilerFaultCodesYour boiler is automatically managing its pump based on the outdoor temperature to prevent your 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: Outside temperature below 1°C: Heating circuit pump ON; Outside temperature above 3°C: Heating circuit pump OFF
What causes this fault?
This code appears when the outdoor temperature sensor detects that the air outside has dropped to near freezing levels. The boiler responds by automatically activating its internal pump to keep water moving through your pipes, which prevents them from freezing and potentially bursting. It is a built-in safety feature rather than a mechanical failure.
This notification will only appear during the colder winter months when external temperatures drop below 1°C.
DIY fix possible
Check if your outdoor sensor is covered by snow or debrisMonitor your radiators to ensure they are getting warm as expectedNo action is required as this is a normal frost protection function
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A boiler cover plan would cover faults like A3:-9 to A3:15 — no call-out fees, no surprises.
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