Low Information
S.6 on Vaillant ecoTEC Plus 635

Your boiler's fan is continuing to run for longer than expected after the heating or hot water has finished.

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

Fan over run

What causes this fault?

This status occurs when the boiler's fan continues to spin after the demand for heating or hot water has ended to clear any remaining combustion gases from the system. While it is usually part of the boiler's normal cooling-down process, it can indicate a minor delay in the communication between the control board and the fan. In rare cases, it may signal that the fan is beginning to wear out or that there is a slight fault with the electrical signals from the main circuit board.

DIY fix possible

Check if the boiler is in a normal cooling phaseMonitor the display to see if the code clears automaticallyPerform a system reset if the fan runs excessivelyEnsure there are no obstructions to the external flue terminal

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Related fault codes

S. 7View →S. 0View →F. 32View →

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