BoilerFaultCodes Blockage High
Boiler Fault Code Blockage
Also written as BLOCKAGE — same fault.
Reviewed by the BoilerFaultCodes Editorial Team Last reviewed
Fault code Blockage 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 has sensed it is getting too hot too quickly and has shut down to prevent damage, usually because water isn't moving through the system properly. (As reported on Main Combi 24)
Pick your boiler brand for the Blockage fix
Source
Information for the Blockage fault code is sourced from the official service / installation manual for each model that displays it. Read more about how we source fault codes →
Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed 7 July 2026