High
FAULT POINT C on Worcester Bosch Greenstar 15sbi

Your boiler's heating system is failing to ignite unless the temperature knobs are turned all the way up, which indicates a problem with the internal sensors or control board.

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

Burner light only with a system boiler demand and user control set to maximum

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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