BoilerFaultCodes L.025 Medium
Boiler Fault Code L.025
Also written as L025 — same fault.
Reviewed by the BoilerFaultCodes Editorial Team Last reviewed
Fault code L.025 appears across 1 boiler brand and 3 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 reading the temperature of the incoming cold water supply, which means it may struggle to provide hot water at the correct temperature. (As reported on Vaillant ecoTEC Plus 836)
Pick your boiler brand for the L.025 fix
Source
Information for the L.025 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