BoilerFaultCodes 5 02 Emergency
Boiler Fault Code 5 02
Also written as 502 — same fault.
Reviewed by the BoilerFaultCodes Editorial Team Last reviewed
Fault code 5 02 appears across 1 boiler brand and 14 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 internal flame activity whilst it is instructed to be off, which is a significant safety concern that requires an immediate professional check. (As reported on Ariston Clas One)
Pick your boiler brand for the 5 02 fix
Source
Information for the 5 02 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