BoilerFaultCodes A3 317 High
Boiler Fault Code A3 317
Also written as A3317 — same fault.
Reviewed by the BoilerFaultCodes Editorial Team Last reviewed
Fault code A3 317 appears across 1 boiler brand and 9 models. The exact meaning varies by manufacturer — pick your boiler brand below to see the model-specific fix.
Most common meaning Your boiler has detected a faulty connection or a broken sensor that monitors the temperature of the exhaust gases, causing the system to shut down for safety. (As reported on Worcester Bosch 26 CDi Xtra)
Pick your boiler brand for the A3 317 fix
Source
Information for the A3 317 fault code is sourced from the official service / installation manual for each model that displays it. Read more about how we source fault codes →
Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed 27 April 2026