BoilerFaultCodes E783 Medium
Boiler Fault Code E783
Reviewed by the BoilerFaultCodes Editorial Team Last reviewed
Fault code E783 appears across 1 boiler brand and 8 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 communication with its smart thermostat or remote control unit, preventing it from receiving instructions on when to turn on the heating or hot water. (As reported on Navien LCB700)
Pick your boiler brand for the E783 fix
Source
Information for the E783 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