F12 Medium

Boiler Fault Code F12

Reviewed by the BoilerFaultCodes Editorial Team Last reviewed

Fault code F12 appears across 6 boiler brands and 30 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 hot water because the internal sensor that monitors water temperature has developed an electrical fault. (As reported on Intergas Rapid 25 32)

Pick your boiler brand for the F12 fix

Ferroli F12 9 models Glow-worm F12 8 models Ideal F12 3 models Intergas F12 3 models Saunier Duval F12 5 models Vaillant F12 2 models

Source

Information for the F12 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