How much does it cost to fix boiler error code 86?

Typical repair cost for the boiler 86 fault is £120-200 including labour.

86 High

Boiler Fault Code 86

Reviewed by the BoilerFaultCodes Editorial Team Last reviewed 7 July 2026

Fault code 86 appears across 3 boiler brands and 11 models. The exact meaning varies by manufacturer — pick your boiler brand below to see the model-specific fix.

Most common meaning Your boiler is receiving an confusing signal from the pipe that brings water back from your radiators, so it has paused operation to prevent any potential strain on the system. (As reported on Ideal Isar M30 / M100)

Pick your boiler brand for the 86 fix

Atag 86 3 models Ideal 86 6 models Keston 86 2 models

Source

Information for the 86 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