BoilerFaultCodesVaillant S.22 Fault Code
Also written as S22 — same fault.
The Vaillant S.22 fault code means: 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.. It appears on 38 Vaillant models in our database.
Technical description: DHW demand – error pump running
What causes the Vaillant S.22 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 fault requires a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.
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Vaillant models that show the S.22 fault code
Click a model for the full fault code list and model-specific repair notes.
- Atmomax Repair: £180-350
- ecoFIT Pure 412
- ecoFIT Pure 418
- ecoFIT Pure 425
- ecoFIT Pure 435
- ecoFIT Pure 825
- ecoFIT Pure 830
- ecoFIT Pure 835
- ecoFIT sustain 615
- ecoFIT sustain 618
- ecoFIT sustain 630
- ecoTEC
- ecoTEC 65kW
- ecoTEC exclusive 627
- ecoTEC plus 412
- ecoTEC plus 415
- ecoTEC plus 418
- ecoTEC plus 424
- ecoTEC plus 430
- ecoTEC Plus 610
- ecoTEC Plus 615
- ecoTEC Plus 620
- ecoTEC Plus 625
- ecoTEC Plus 630
- ecoTEC Plus 635
- ecoTEC plus 637 Repair: £180-450
- ecoTEC Plus 826
- ecoTEC Plus 832
- ecoTEC Plus 840
- ecoTEC Plus 938
- ecoTEC Pro
- ecoTEC Pro / ecoTEC Plus Repair: £180-450
- ecoTEC Pro 24
- ecoTEC Pro 28
- ecoTEC Pro 30
- ecoTEC sustain
- Home Combi
- Home System
Source
Vaillant S.22 fault code information on this page is sourced and cross-checked against the official Vaillant service / installation manuals for each affected model.
- Vaillant ecoFIT Pure 425 manual (PDF)
- Vaillant ecoFIT Pure 835 manual (PDF)
- Vaillant ecoFIT sustain 630 manual (PDF)
Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed 31 August 2026