Boiler Fault Code 1 bar

Also written as 1BAR — same fault.

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

Fault code 1 bar 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 pressure is too low, which prevents it from heating the water properly. (As reported on Sime Dewy 30/50 HE WM)