High Lockout
C6 on Worcester Bosch Greenstar 30HE

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

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 high.

What causes this fault?

This fault occurs when the boiler's internal computer detects that the fan is spinning at a higher speed than required for safe combustion. It is typically caused by a faulty sensor within the fan motor itself or a communication error from the main control board, which prevents the boiler from regulating the airflow correctly.

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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