BoilerFaultCodes Er09 Emergency
Boiler Fault Code Er09
Also written as ER09 — same fault.
Reviewed by the BoilerFaultCodes Editorial Team Last reviewed
Fault code Er09 appears across 1 boiler brand and 2 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 its exhaust system or the sensor that monitors exhaust heat, causing it to shut down for safety. (As reported on Biasi Concept 400 20 1 Mfs)
Pick your boiler brand for the Er09 fix
Source
Information for the Er09 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 31 August 2026