Low
S.97 on Vaillant ecoTEC Plus 635

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.

Technical description

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

DIY fix possible

Wait for the boiler to complete its automatic self-test cycleMonitor the display to see if the status changes back to normal operationIf the code persists for more than 15 minutes, try resetting the boiler

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Related fault codes

F.22View →F.73View →F.74View →

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