BoilerFaultCodes E278 High
Boiler Fault Code E278
Reviewed by the BoilerFaultCodes Editorial Team Last reviewed
Fault code E278 appears across 1 boiler brand and 4 models. The exact meaning varies by manufacturer — pick your boiler brand below to see the model-specific fix.
Most common meaning Your boiler is having trouble measuring its own internal temperature, so it has shut down to prevent it from getting too hot or cold. (As reported on Navien NCB 28 HE)
Pick your boiler brand for the E278 fix
Source
Information for the E278 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