BoilerFaultCodes F.80 High
Boiler Fault Code F.80
Also written as F80 — same fault.
Reviewed by the BoilerFaultCodes Editorial Team Last reviewed
Fault code F.80 appears across 2 boiler brands and 4 models. The exact meaning varies by manufacturer — pick your boiler brand below to see the model-specific fix.
Most common meaning Your boiler is struggling to accurately detect water temperatures because a sensor responsible for monitoring the heat exchange process has developed a connection fault. (As reported on Vaillant ecoTEC Plus 826)
Pick your boiler brand for the F.80 fix
Source
Information for the F.80 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