Connection High
Boiler Fault Code Connection
Also written as CONNECTION — same fault.
Reviewed by the BoilerFaultCodes Editorial Team Last reviewed
Fault code Connection appears across 2 boiler brands and 22 models. The exact meaning varies by manufacturer — pick your boiler brand below to see the model-specific fix.
Most common meaning Your boiler's main internal computer and the front control panel have lost contact, meaning the system cannot receive instructions to provide heating or hot water. (As reported on Glow-worm Ultimate 3 25R)
Pick your boiler brand for the Connection fix
Source
Information for the Connection 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