Emergency
Slow flash (unspecified rate) on Worcester Bosch Greenstar 12Ri

Your boiler has detected that it cannot safely get rid of exhaust gases, so it has stopped working to prevent a buildup of dangerous fumes.

Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed

Act immediately

Turn off your boiler and stop using gas appliances. Call a Gas Safe engineer now. This fault can be dangerous if ignored.

Technical description

Flue pressure switch: Blockage in the flue system.

Engineer required

This is a emergency severity fault. Stop using the boiler and call a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.

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