Boiler Fault Code B@%

Also written as B — same fault.

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

Fault code B@% appears across 4 boiler brands and 10 models. The exact meaning varies by manufacturer — pick your boiler brand below to see the model-specific fix.

Most common meaning Your boiler is overheating too quickly because water isn't moving through the system fast enough, causing it to take a ten-minute break to cool down. (As reported on Remeha Quinta 30)