How much does it cost to fix Worcester Bosch error code 317 A3?

Typical repair cost for the Worcester Bosch 317 A3 fault is £150-250 including labour.

317 A3 Emergency

Worcester Bosch 317 A3 Fault Code

Q: What does the Worcester Bosch 317 A3 fault code mean?

Your boiler has detected an electrical fault with the internal sensor that monitors the safety of the exhaust gasses, causing it to automatically shut down to prevent unsafe operation.

Also written as 317A3 — same fault.

The Worcester Bosch 317 A3 fault code means: your boiler has detected an electrical fault with the internal sensor that monitors the safety of the exhaust gasses, causing it to automatically shut down to prevent unsafe operation.. It appears on 3 Worcester Bosch models in our database.

Technical description: Flue gas sensor shorted

Typical repair cost £150-250 (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 317 A3 fault code

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

Source

Worcester Bosch 317 A3 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