d.xx Low

Ariston d.xx Fault Code

Also written as DXX — same fault.

The Ariston d.xx fault code means: your boiler is simply showing you the target room temperature you have selected while you are adjusting the heating control knob.. It appears on 3 Ariston models in our database.

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: Room temperature set (while turning the heating temperature knob; 'xx' represents the temperature)

DIY fix possible

No action is required as this is a normal status messageRotate the knob to your desired comfort temperatureWait a few seconds for the display to return to the standard pressure or temperature view

Find a Gas Safe engineer

Search the official register for a qualified engineer in your area.

Gas Safe Register →

Ariston models that show the d.xx fault code

Click a model for the full fault code list and model-specific repair notes.

Source

Ariston d.xx fault code information on this page is sourced and cross-checked against the official Ariston service / installation manuals for each affected model.

Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed 27 April 2026