High
306 V on Worcester Bosch Heatslave

Your boiler is still detecting a flame even after it has tried to shut off the fuel supply, which is a safety conflict preventing the system from running.

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

Flame signal after closing the fuel supply – the air/gas ratio control valve might need replacing

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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