D.61 High

Vaillant D.61 Fault Code

Also written as D61 — same fault.

The Vaillant D.61 fault code means: your boiler is recording that it has repeatedly failed to light or stay on, leading to multiple safety shutdowns.. It appears on 37 Vaillant models in our database.

Call an engineer soon

Book a Gas Safe engineer within 24 to 48 hours. Your boiler may be unsafe or could break down completely if left.

Technical description: Number of unsuccessful lockouts

What causes the Vaillant D.61 fault?

This fault occurs when the boiler tries to ignite multiple times but fails to establish a stable flame, causing the system to lock out for safety. The most common reasons include a lack of gas supply, worn-out ignition parts that can no longer spark, or a build-up of carbon on the electrodes that prevents the boiler from 'sensing' the flame.

This fault is more common during extreme cold spells, as frozen external gas regulators or blockages in the flue can prevent the consistent gas flow and ventilation required for ignition.

Typical repair cost £120-450 (including labour)

Engineer required

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

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Vaillant models that show the D.61 fault code

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

Source

Vaillant D.61 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