BoilerFaultCodes 344 Emergency
Boiler Fault Code 344
Reviewed by the BoilerFaultCodes Editorial Team Last reviewed
Fault code 344 appears across 2 boiler brands and 5 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 the exhaust gases are becoming dangerously hot while the water inside the unit remains cold, suggesting a blockage or a failure in the heat transfer process. (As reported on Worcester Bosch Greenstar CDi Compact)
Pick your boiler brand for the 344 fix
Source
Information for the 344 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 7 July 2026