Boiler Fault Code D4 286

Also written as D4286 — same fault.

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

Fault code D4 286 appears across 1 boiler brand and 9 models. The exact meaning varies by manufacturer — pick your boiler brand below to see the model-specific fix.

Most common meaning Your boiler has shut down because it thinks the water returning to it is dangerously hot, which usually means the water isn't circulating properly through your radiators. (As reported on Worcester Bosch 24 RSF)