BoilerFaultCodes 4 flashes green High
Boiler Fault Code 4 flashes green
Also written as 4FLASHESGREEN — same fault.
Reviewed by the BoilerFaultCodes Editorial Team Last reviewed
Fault code 4 flashes green 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 internal computer is struggling to talk to its internal parts, meaning it has paused operations as a safety precaution until the signal issue is resolved. (As reported on Main Insul 7)
Pick your boiler brand for the 4 flashes green fix
Source
Information for the 4 flashes green 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