d.19 Low

Vaillant d.19 Fault Code

Also written as D19 — same fault.

The Vaillant d.19 fault code means: this code indicates the boiler is currently adjusting its internal water pump speed to match the heating or hot water demand, which is a standard part of its normal operating cycle.. It appears on 6 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: Pumpoperatingmode,2stagepump

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.19 fault code

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

Source

Vaillant d.19 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