d.06 Low

Vaillant d.06 Fault Code

Also written as D06 — same fault.

The Vaillant d.06 fault code means: your boiler is simply displaying the temperature setting currently requested for your hot water, which is a normal status notification rather than a fault.. It appears on 12 Vaillant 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: Hot water set target temperature (Combination unit only)

DIY fix possible

Check your user manual to confirm if this code is appearing as a temporary status displayPress the 'i' button on your boiler display to return to the standard temperature viewIf the boiler is operating normally, no action is required

Find a Gas Safe engineer

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

Gas Safe Register →
Boiler cover options

Avoid the next call-out bill

A cover plan would handle faults like d.06: no call-out fees, no surprise bills.

Approved partner
Domestic Appliance Guard
Unlimited call-outs, 24/7 helpline, no price-hike promise
Get a quote →

Affiliate links. We may earn a commission at no extra cost to you.

Vaillant models that show the d.06 fault code

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

Source

Vaillant d.06 fault code information on this page is sourced and cross-checked against the official Vaillant service / installation manuals for each affected model.

Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed 31 August 2026