BoilerFaultCodes 375 / E4 Medium
Boiler Fault Code 375 / E4
Also written as 375E4 — same fault.
Reviewed by the BoilerFaultCodes Editorial Team Last reviewed
Fault code 375 / E4 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 is having trouble reading the temperature of the incoming cold water, which may cause your hot water to fluctuate in temperature or not heat up correctly. (As reported on Worcester Bosch Greenstar CDi Compact)
Pick your boiler brand for the 375 / E4 fix
Source
Information for the 375 / E4 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