Fb 365 Emergency

Worcester Bosch Fb 365 Fault Code

Also written as FB365 — same fault.

The Worcester Bosch Fb 365 fault code means: your boiler has detected a potential issue with its internal gas control mechanism and has safely shut itself down to prevent any risk.. It appears on 4 Worcester Bosch models in our database.

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: Gas valve EV1 leak test failed - Gas valve leak.
Typical repair cost £200-350 (including labour)

Engineer required

This fault requires a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.

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Worcester Bosch models that show the Fb 365 fault code

Click a model for the full fault code list and model-specific repair notes.

Source

Worcester Bosch Fb 365 fault code information on this page is sourced and cross-checked against the official Worcester Bosch service / installation manuals for each affected model.

Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed 7 July 2026