High
A3 317 on Worcester Bosch 30i Junior

Your boiler has detected an electrical fault with a sensor that monitors the safety of the exhaust gases, causing the system to shut down for protection.

Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed

Call an engineer soon

Book a Gas Safe engineer within 24 to 48 hours. Your boiler may be unsafe or could break down completely if left.

Technical description

Short circuit in the flue gas temperature sensor contacts

Engineer required

This is a high severity fault. Stop using the boiler and call a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.

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Related fault codes

E9View →

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