BoilerFaultCodes 86 H.....2..... High
Boiler Fault Code 86 H.....2.....
Also written as 86H2 — same fault.
Reviewed by the BoilerFaultCodes Editorial Team Last reviewed
Fault code 86 H.....2..... 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 having trouble measuring the temperature of the water returning to it, which causes it to stop working as a safety precaution. (As reported on Ideal Isar M30 / M100)
Pick your boiler brand for the 86 H.....2..... fix
Source
Information for the 86 H.....2..... 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