205 Emergency

Boiler Fault Code 205

Reviewed by the BoilerFaultCodes Editorial Team Last reviewed

Fault code 205 appears across 2 boiler brands 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 an issue with the air intake or exhaust system, meaning it cannot safely vent gases and has shut down to protect your home. (As reported on Navien NCB CE)

Pick your boiler brand for the 205 fix

Navien 205 5 models Worcester Bosch 205 4 models

Source

Information for the 205 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 7 July 2026