Low
S.97 on Vaillant ecoTEC Plus 938

Your boiler is currently performing an internal health check on its sensors and has temporarily paused heating and hot water to ensure everything is functioning safely.

Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed

Monitor it

This is a minor fault. Keep an eye on it and mention it at your next annual boiler service. Reset the boiler and see if it clears.

What the manual says

Manufacturer manual

Automatic test programme: Water pressure sensor, heating and hot water request blocked.

From this model's manual
Verified against the Vaillant Ecotec Plus 826 installation & service manual, page 48.
Plain-English guidance below. Severity, DIY steps, costs and parts are our interpretation to help you act, not text from the manual.

DIY fix possible

Wait for the boiler to complete the automatic test cycle (usually takes a few minutes).Monitor the display to see if the boiler returns to a normal status code (e.g., S.0 or S.4).If the code persists for over 15 minutes, try a manual reset via the button with the flame symbol.

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