Low
d.40 on Vaillant ecoFIT Pure 418

Your boiler is displaying its current heating water temperature and this is a normal status reading rather than a breakdown code.

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

Heating flow temperature

DIY fix possible

Check if the boiler is still providing heating and hot water as normalObserve if the number fluctuates, as this represents the changing temperature of the waterNo action is required unless the boiler stops working or shows an 'F' fault code

Find a Gas Safe engineer
Search the official register →

Related fault codes

Related guides you might find useful