BoilerFaultCodes B LED 4 High
Boiler Fault Code B LED 4
Also written as BLED4 — same fault.
Reviewed by the BoilerFaultCodes Editorial Team Last reviewed
Fault code B LED 4 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 stopped working because it cannot correctly sense its own temperature, likely due to a loose wire or a faulty temperature probe. (As reported on Ferroli Arean)
Pick your boiler brand for the B LED 4 fix
Source
Information for the B LED 4 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