E23 High

Boiler Fault Code E23

Reviewed by the BoilerFaultCodes Editorial Team Last reviewed

Fault code E23 appears across 6 boiler brands and 28 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 fault with the sensor that monitors exhaust gases, and as a safety precaution, it will not operate until this is fixed. (As reported on Ravenheat CSI 120)

Pick your boiler brand for the E23 fix

Ariston E23 5 models Biasi E23 3 models Ferroli E23 1 model Keston E23 9 models Ravenheat E23 9 models Vokera E23 1 model

Source

Information for the E23 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