Low
d.31 on Vaillant ecoTEC Plus 620

This code is simply an information display showing whether your boiler is set to fill itself automatically, semi-automatically, or requires you to do it manually.

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 filling device: 0=Manual, 1=Semi-automatic, 2=Automatic

DIY fix possible

Navigate to the boiler's settings menuLocate the d.31 diagnostic menuAdjust the value to match your specific installation requirements, typically 1 if you have a built-in filling loop

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Related fault codes

F.22View →F.24View →

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