BoilerFaultCodes 307 High
Boiler Fault Code 307
Reviewed by the BoilerFaultCodes Editorial Team Last reviewed
Fault code 307 appears across 2 boiler brands 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 its connection to the energy grid while trying to operate independently, causing the system to shut down for safety. (As reported on Navien NCM 1130HH)
Pick your boiler brand for the 307 fix
Source
Information for the 307 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 31 August 2026