Low
C4 273 on Worcester Bosch Danesmoor

Your boiler's safety system is detecting air movement when the fan should be off, which is usually caused by strong winds or a blocked exhaust pipe.

Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed

Monitor it

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

Airflow present during last 24 hour

DIY fix possible

Check the external flue pipe (exhaust) for any obstructions like bird nests, leaves, or debrisEnsure there are no items leaning against the flue terminal outsidePress the 'Reset' button on the boiler control panel once

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