Boiler Fault Code Block 11

Also written as BLOCK11 — same fault.

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

Fault code Block 11 appears across 1 boiler brand and 6 models. The exact meaning varies by manufacturer — pick your boiler brand below to see the model-specific fix.

Most common meaning Your boiler has detected that the water inside is heating up much too quickly compared to how fast it is moving around your pipes, so it has temporarily paused your heating to prevent internal damage. (As reported on Atag E Range)