BoilerFaultCodes -. / Y High
Boiler Fault Code -. / Y
Also written as Y — same fault.
Reviewed by the BoilerFaultCodes Editorial Team Last reviewed
Fault code -. / Y 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 is stuck on the heating setting and cannot control its temperature properly, leading to overheating or a lack of hot water. (As reported on Ideal Maximiser SE)
Pick your boiler brand for the -. / Y fix
Source
Information for the -. / Y 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 27 April 2026