BoilerFaultCodes Water level control: lock out High
Boiler Fault Code Water level control: lock out
Also written as WATERLEVELCONTROLLOCKOUT — same fault.
Reviewed by the BoilerFaultCodes Editorial Team Last reviewed
Fault code Water level control: lock out 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 switched itself off because it cannot properly detect the water level, which is a safety measure to prevent the system from running dry. (As reported on Remeha Gas 620-510)
Pick your boiler brand for the Water level control: lock out fix
Source
Information for the Water level control: lock out 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 27 April 2026