Low Information
S.31 on Vaillant ecoTEC Pro 24

Your boiler is currently set to 'Summer Mode', meaning the heating is switched off while hot water remains available.

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

Current unit status (example shown in installer level overview)

What causes this fault?

This status appears because the central heating temperature control on the front of the boiler has been turned all the way to the off position. It physically prevents the boiler from sending heat to your radiators while still allowing it to provide hot water to your taps. It is a user setting rather than a mechanical failure, often used to save energy during warmer months.

This code is most frequently seen during the summer months when homeowners manually disable their heating to prevent the radiators from coming on.

DIY fix possible

Locate the radiator symbol knob or button on the control panelTurn the dial clockwise or press the button to increase the heating temperatureThe display should change from S.31 to a temperature or a different status code like S.04

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