D.041 Medium

Vaillant D.041 Fault Code

Also written as D041 — same fault.

The Vaillant D.041 fault code means: your boiler is struggling to detect the temperature of the water coming back into the system, which can cause it to stop working correctly or shut down to protect itself.. It appears on 7 Vaillant models in our database.

Book a service

This fault should be looked at by a Gas Safe engineer within the next week or two. It may get worse if left.

Technical description: Returntemperatureactualvalue
Typical repair cost £120-250 (including labour)

Engineer required

This fault requires a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.

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.041: 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.041 fault code

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

Source

Vaillant D.041 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 7 July 2026