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

Typical repair cost for the boiler F.86 fault is £90-180 including labour.

F.86 High

Boiler Fault Code F.86

Also written as F86 — same fault.

Reviewed by the BoilerFaultCodes Editorial Team Last reviewed 27 April 2026

Fault code F.86 appears across 1 boiler brand and 24 models. The exact meaning varies by manufacturer — pick your boiler brand below to see the model-specific fix.

Most common meaning Your boiler has stopped providing heat because a safety limit switch for your underfloor heating has been triggered or disconnected. (As reported on Vaillant ecoTEC plus)

Pick your boiler brand for the F.86 fix

Vaillant F.86 24 models

Source

Information for the F.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 27 April 2026