BoilerFaultCodes 4 (Flashing) Low
Boiler Fault Code 4 (Flashing)
Also written as 4FLASHING — same fault.
Reviewed by the BoilerFaultCodes Editorial Team Last reviewed
Fault code 4 (Flashing) 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 working correctly and is currently in standby mode, waiting for a signal from your thermostat or hot water tap to start. (As reported on Ferroli Tempra 12 18)
Pick your boiler brand for the 4 (Flashing) fix
Source
Information for the 4 (Flashing) 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