Emergency
264 on Worcester Bosch Greenstar 12i System

Your boiler has detected that the air supply needed for safe combustion has been interrupted while it was trying to run.

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.

What the manual says

Manufacturer manual

C1 Airflow stopped during operation

From this model's manual
Verified against the Worcester Bosch Greenstar 12i System installation & service manual, page 63.
Plain-English guidance below. Severity, DIY steps, costs and parts are our interpretation to help you act, not text from the manual.

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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