BoilerFaultCodes F.538 Medium
Boiler Fault Code F.538
Also written as F538 — same fault.
Reviewed by the BoilerFaultCodes Editorial Team Last reviewed
Fault code F.538 appears across 1 boiler brand and 2 models. The exact meaning varies by manufacturer — pick your boiler brand below to see the model-specific fix.
Most common meaning Your boiler has lost communication with the temperature sensor that tracks the return flow from your solar thermal heating system, meaning it can no longer accurately monitor heat coming from your solar panels. (As reported on Viessmann Vitodens 222-F B2TF)
Pick your boiler brand for the F.538 fix
Source
Information for the F.538 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