How much does it cost to fix boiler error code F51?

Typical repair cost for the boiler F51 fault is £120-200 including labour.

F51 High

Boiler Fault Code F51

Reviewed by the BoilerFaultCodes Editorial Team Last reviewed 7 July 2026

Fault code F51 appears across 3 boiler brands and 14 models. The exact meaning varies by manufacturer — pick your boiler brand below to see the model-specific fix.

Most common meaning Your boiler has detected a faulty connection in the sensor that monitors the temperature of your hot water, which is preventing the system from heating water for your taps. (As reported on Viessmann Vitopend 100)

Pick your boiler brand for the F51 fix

ECA F51 4 models Ferroli F51 8 models Viessmann F51 2 models

Source

Information for the F51 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