Low
d.40 on Vaillant aquaPLUS

Your boiler is currently displaying the live temperature of the water flowing through the system rather than a 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.

Technical description

Actual flow temperature

DIY fix possible

No action is required as this is an informational status code.Press the 'i' button to exit the information menu if you wish to see the system pressure.If the boiler is not firing, check that your thermostat is turned up and calling for heat.

Find a Gas Safe engineer
Search the official register →

Related fault codes

d.41View →S.04View →S.24View →

Related guides you might find useful

Yellow or orange flame — CO safety

Safety-critical — turn off, read this.

Read →

Is boiler cover worth it?

Break-even maths on monthly cover.

Read →

When to replace your boiler

7 signs repair isn't worth it anymore.

Read →