Boiler Fault Code H:01 .18

Also written as H0118 — same fault.

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

Fault code H:01 .18 appears across 1 boiler brand and 8 models. The exact meaning varies by manufacturer — pick your boiler brand below to see the model-specific fix.

Most common meaning Your boiler is failing to move hot water around your radiators or taps, likely because it detects a blockage or a pump issue that prevents it from running safely. (As reported on Baxi Combi 224, 228, 424, 428)