BoilerFaultCodes N.343 Medium
Boiler Fault Code N.343
Also written as N343 — same fault.
Reviewed by the BoilerFaultCodes Editorial Team Last reviewed
Fault code N.343 appears across 1 boiler brand and 3 models. The exact meaning varies by manufacturer — pick your boiler brand below to see the model-specific fix.
Most common meaning Your boiler is struggling to accurately measure the air it needs for combustion, so it is running in a limited state to remain operational. (As reported on Vaillant ecoTEC plus)
Pick your boiler brand for the N.343 fix
Source
Information for the N.343 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