BoilerFaultCodes N.100 Low
Boiler Fault Code N.100
Also written as N100 — same fault.
Reviewed by the BoilerFaultCodes Editorial Team Last reviewed
Fault code N.100 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 has lost the connection to the thermometer placed outside your home, so it can no longer automatically adjust your heating based on the weather. (As reported on Vaillant ecoTEC plus)
Pick your boiler brand for the N.100 fix
Source
Information for the N.100 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