High Lockout
C6 on Worcester Bosch Greenstar 25HE

Your boiler has stopped working because the fan that clears away waste gases has failed to start or is spinning too slowly.

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 not running

What causes this fault?

This fault occurs when the boiler’s safety system detects that the fan is not moving enough air to safely vent combustion gases out of the flue. The most common reasons are a build-up of dirt causing the fan to seize, a mechanical failure of the fan motor, or a fault on the main control board failing to send power to the component.

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 →C4View →

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