How much does it cost to fix boiler error code F39?

Typical repair cost for the boiler F39 fault is £120-200 including labour.

F39 Low

Boiler Fault Code F39

Reviewed by the BoilerFaultCodes Editorial Team Last reviewed 7 July 2026

Fault code F39 appears across 4 boiler brands and 20 models. The exact meaning varies by manufacturer — pick your boiler brand below to see the model-specific fix.

Most common meaning Your boiler is having trouble communicating with the outdoor weather sensor, which means it cannot automatically adjust its temperature based on outside conditions. (As reported on Ferroli Modena HE)

Pick your boiler brand for the F39 fix

ECA F39 4 models Euroterm F39 1 model Ferroli F39 14 models Viessmann F39 1 model

Source

Information for the F39 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