High Lockout
S.22 on Vaillant ecoTEC Pro / ecoTEC Plus

Your boiler has detected that hot water is being called for, but it believes the pump is running when it shouldn't be or there is a circulation issue preventing proper operation.

Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed

Call an engineer soon

Book a Gas Safe engineer within 24 to 48 hours. Your boiler may be unsafe or could break down completely if left.

Technical description

DHW demand – error pump running

What causes this fault?

This fault occurs when the boiler detects a conflict in the heating water flow while trying to provide hot water. It usually means the internal pump is stuck in the ‘on’ position or a sensor is sending incorrect signals to the main control board about water movement. This prevents the boiler from safely managing the temperature, leading to a shutdown to protect internal components.

Engineer required

This is a high severity fault. Stop using the boiler and call a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.

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Related fault codes

F.22View →F.75View →S.24View →

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