BoilerFaultCodes E593 Medium
Boiler Fault Code E593
Reviewed by the BoilerFaultCodes Editorial Team Last reviewed
Fault code E593 appears across 1 boiler brand and 1 models. The exact meaning varies by manufacturer — pick your boiler brand below to see the model-specific fix.
Most common meaning Your boiler's electronic control panel is experiencing a communication error, meaning it cannot properly register your inputs or display settings. (As reported on Navien NCB)
Pick your boiler brand for the E593 fix
Source
Information for the E593 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