306 Emergency

Worcester Bosch 306 Fault Code

The Worcester Bosch 306 fault code means: your boiler has detected that a flame is still present even though it has tried to turn the gas supply off, which indicates a potential safety control issue.. It appears on 6 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: Flame signal after closing the fuel supply

What causes the Worcester Bosch 306 fault?

Unexpected flame detection

Typical repair cost £150-300 (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 306 fault code

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

Source

Worcester Bosch 306 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 31 August 2026