High
C4 / 273 on Worcester Bosch Greenstar i

Your boiler has detected that its exhaust fan has been running non-stop for the last day, so it has locked itself to prevent potential overheating or damage.

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

Continuous fan operation for the last 24 hours (appliance temporary blocked)

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

C6View →EAView →

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