Low
D.40 on Vaillant Atmomax

Your boiler is currently showing you what temperature it is aiming to reach rather than a specific fault code.

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.

What the manual says

Manufacturer manual

Flow temperature target value

Shared across the range
This code is shared by the boilers in this range, which use the same control board. It may not be printed in this exact variant’s manual.
Plain-English guidance below. Severity, DIY steps, costs and parts are our interpretation to help you act, not text from the manual.

DIY fix possible

Check if your thermostat is set too high or too lowMonitor the display to see if it changes to a standard temperature readingNo action is required as this is an information status rather than a breakdown

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Related fault codes

D.41View →S.04View →

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