Boiler Fault Code 2/3/5

Also written as 235 — same fault.

Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed 7 July 2026

Fault code 2/3/5 appears across 1 boiler brand and 1 models. The exact meaning varies by manufacturer — pick your boiler brand below to see the model-specific fix.

Most common meaning Your boiler's internal computer or its communication module has developed a critical fault, preventing it from safely starting or controlling your heating and hot water. (As reported on Worcester Bosch GB162)