E40 High

Boiler Fault Code E40

Reviewed by the BoilerFaultCodes Editorial Team Last reviewed

Fault code E40 appears across 10 boiler brands and 58 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 that a temperature sensor responsible for monitoring water returning to the unit has disconnected or broken, preventing it from running safely. (As reported on Potterton Powermax HE)

Pick your boiler brand for the E40 fix

Alpha E40 6 models Baxi E40 24 models Biasi E40 5 models Ferroli E40 1 model Keston E40 9 models Main E40 1 model Potterton E40 4 models Remeha E40 6 models Vokera E40 1 model Warmhaus E40 1 model

Source

Information for the E40 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