Boiler Fault Code 349 / EF

Also written as 349EF — same fault.

Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed 27 April 2026

Fault code 349 / EF 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 detected that it is heating up or cooling down much faster than expected while running at its lowest setting, which typically indicates a blockage or a failure in how water is flowing through the system. (As reported on Worcester Bosch Greenstar CDi Compact)