F20 High

Boiler Fault Code F20

Reviewed by the BoilerFaultCodes Editorial Team Last reviewed

Fault code F20 appears across 5 boiler brands and 29 models. The exact meaning varies by manufacturer — pick your boiler brand below to see the model-specific fix.

Most common meaning Your boiler's internal computer parts are having trouble communicating with each other, causing the system to shut down for safety. (As reported on Saunier Duval Isotwin F30E)

Pick your boiler brand for the F20 fix

Ferroli F20 1 model Glow-worm F20 12 models Heatline F20 8 models Saunier Duval F20 6 models Vaillant F20 2 models

Source

Information for the F20 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