Low
d.40 on Vaillant ecoTEC plus Aquaplus

This code is simply a status message showing the current temperature of the water flowing through your heating system, not an error or a fault with your boiler.

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

Actual flow temperature

DIY fix possible

This fault may be fixable without an engineer. Check your manual first.

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Related fault codes

d.41View →d.00View →

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