Emergency
Pulsation on start on Worcester Bosch Utility

Your boiler is struggling to ignite smoothly because the air and fuel mixture is incorrect or there is a blockage in the flue, causing it to shudder when it starts up.

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

CF - Flue draught incorrect; Combustion settings incorrect; Faulty nozzle

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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