BoilerFaultCodes Safety indicator (4) lights Emergency
Boiler Fault Code Safety indicator (4) lights
Also written as SAFETYINDICATOR4LIGHTS — same fault.
Reviewed by the BoilerFaultCodes Editorial Team Last reviewed
Fault code Safety indicator (4) lights appears across 1 boiler brand and 2 models. The exact meaning varies by manufacturer — pick your boiler brand below to see the model-specific fix.
Most common meaning Your boiler has detected a safety issue and has shut itself down to prevent any potential danger. (As reported on Saunier Duval Opalia)
Pick your boiler brand for the Safety indicator (4) lights fix
Source
Information for the Safety indicator (4) lights 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