Boiler Fault Code d.02

Also written as D02 — same fault.

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

Fault code d.02 appears across 3 boiler brands and 35 models. The exact meaning varies by manufacturer — pick your boiler brand below to see the model-specific fix.

Most common meaning Your boiler is currently taking a mandatory rest period to prevent the system from cycling on and off too frequently, and it will resume heating automatically once this time expires. (As reported on Glow-worm Sustain 12s)