138 Low

Boiler Fault Code 138

Reviewed by the BoilerFaultCodes Editorial Team Last reviewed

Fault code 138 appears across 1 boiler brand and 1 models. The exact meaning varies by manufacturer — pick your boiler brand below to see the model-specific fix.

Most common meaning Your boiler is currently running a specialized drying programme for a new underfloor heating installation, which is a normal process and not a fault. (As reported on Alpha E-Tec Plus NX)

Pick your boiler brand for the 138 fix

Alpha 138 1 model

Source

Information for the 138 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