Low Information
D.25 on Vaillant ecoTEC plus Regular

Your boiler is simply letting you know that your external smart thermostat or system controller has successfully requested hot water.

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

Hot water activation via ebus control

What causes this fault?

This code appears when your external smart thermostat or system controller sends a digital signal to the boiler asking it to heat your hot water cylinder. It is not a malfunction, but rather a status update showing that the communication between your controls and the boiler is working correctly. You will typically see this on the screen whenever your programmed hot water schedule is active.

DIY fix possible

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

Find a Gas Safe engineer
Search the official register →

Related fault codes

D.23View →

Related guides you might find useful

No hot water but heating works

Almost always a stuck diverter valve on combis.

Read →

Boiler won't turn on — 9-step checklist

Work through these before the call-out.

Read →

Yellow or orange flame — CO safety

Safety-critical — turn off, read this.

Read →