BoilerFaultCodes 85 H.....1..... High
Boiler Fault Code 85 H.....1.....
Also written as 85H1 — same fault.
Reviewed by the BoilerFaultCodes Editorial Team Last reviewed
Fault code 85 H.....1..... 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 lost the ability to accurately measure the water temperature, so it has shut down to prevent overheating. (As reported on Ideal Isar M30 / M100)
Pick your boiler brand for the 85 H.....1..... fix
Source
Information for the 85 H.....1..... 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