Boiler Fault Code 285 / E9

Also written as 285E9 — same fault.

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

Fault code 285 / E9 appears across 1 boiler brand and 3 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 returning to it is much too hot, so it has safely shut itself down to prevent damage. (As reported on Worcester Bosch Greenstar CDi Compact)