BoilerFaultCodes F1 (259) High
Boiler Fault Code F1 (259)
Also written as F1259 — same fault.
Reviewed by the BoilerFaultCodes Editorial Team Last reviewed
Fault code F1 (259) appears across 1 boiler brand 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's internal computer is experiencing a critical error and can no longer safely control the heating system, meaning the boiler has shut down to prevent further issues. (As reported on Worcester Bosch Greenstar 12i System)
Pick your boiler brand for the F1 (259) fix
Source
Information for the F1 (259) 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