High Lockout
C1 on Worcester Bosch Greenstar 30HE

Your boiler has stopped working because the internal fan, which clears exhaust gases, isn't spinning fast enough to operate safely.

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 speed too low.

What causes this fault?

This fault occurs when the boiler's control system detects that the fan isn't reaching the necessary speed to safely push exhaust fumes out of the flue. The most common reasons are a build-up of dirt inside the fan mechanism, a block in the air supply tubes, or the electronic controller failing to send enough power to the motor.

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

C4View →C6View →A8View →

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