High
C4 on Worcester Bosch Worcester 25/30 HE

Your boiler's internal fan is running constantly and won't shut down, preventing the system from starting its normal ignition sequence.

Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed

Call an engineer soon

Book a Gas Safe engineer within 24 to 48 hours. Your boiler may be unsafe or could break down completely if left.

Technical description

Fan does not switch off

Engineer required

This is a high severity fault. Stop using the boiler and call a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.

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Related fault codes

C1View →C6View →

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