BoilerFaultCodes 342 D4 High
Boiler Fault Code 342 D4
Also written as 342D4 — same fault.
Reviewed by the BoilerFaultCodes Editorial Team Last reviewed
Fault code 342 D4 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 the water inside is heating up much faster than it is supposed to, which often means there is not enough water flowing through the system to carry the heat away properly. (As reported on Worcester Bosch Greenstar CDi Compact)
Pick your boiler brand for the 342 D4 fix
Source
Information for the 342 D4 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