BoilerFaultCodes F43 High
Boiler Fault Code F43
Reviewed by the BoilerFaultCodes Editorial Team Last reviewed
Fault code F43 appears across 2 boiler brands and 23 models. The exact meaning varies by manufacturer — pick your boiler brand below to see the model-specific fix.
Most common meaning Your boiler has shut down to prevent the heat exchanger from overheating, often because the water isn't flowing through the system correctly. (As reported on Ferroli Bluehelix Tech)
Pick your boiler brand for the F43 fix
Source
Information for the F43 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