How much does it cost to fix Worcester Bosch error code 347?

Typical repair cost for the Worcester Bosch 347 fault is £120-280 including labour.

347 High

Worcester Bosch 347 Fault Code

Q: What does the Worcester Bosch 347 fault code mean?

Your boiler has stopped because the water returning from your radiators is hotter than the water leaving the boiler, which usually means the internal sensors are confused or the water is flowing the wrong way.

The Worcester Bosch 347 fault code means: your boiler has stopped because the water returning from your radiators is hotter than the water leaving the boiler, which usually means the internal sensors are confused or the water is flowing the wrong way.. It appears on 3 Worcester Bosch models in our database.

Technical description: Return temp exceeds flow temp for over 20 sec

Typical repair cost £120-280 (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 347 fault code

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

Source

Worcester Bosch 347 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 27 April 2026