High Lockout
C6 on Worcester Bosch Greenstar 12i System

Your boiler's internal fan is spinning faster than it should, which has caused the system to shut down for safety.

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 running too fast

What causes this fault?

This fault occurs when the boiler's control system loses the ability to regulate the fan, causing it to spin at an unsafe speed. The most common reason is an electrical failure within the fan's internal motor or a malfunctioning circuit board that is sending incorrect voltage 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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