BoilerFaultCodes D.118-5 Emergency
Boiler Fault Code D.118-5
Also written as D1185 — same fault.
Reviewed by the BoilerFaultCodes Editorial Team Last reviewed
Fault code D.118-5 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 internal issue with its safety monitoring sensor, which prevents it from operating to ensure your home remains safe. (As reported on Vaillant ecoTEC exclusive)
Pick your boiler brand for the D.118-5 fix
Source
Information for the D.118-5 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