346 Emergency

Worcester Bosch 346 Fault Code

The Worcester Bosch 346 fault code means: your boiler is overheating because the temperature of the gases escaping through the flue is rising much faster than it should, causing the system to shut down for safety.. 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: EC Flue gas temperature rising too fast
Typical repair cost £180-350 (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 346 fault code

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

Source

Worcester Bosch 346 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