D.83 Low

Vaillant D.83 Fault Code

Also written as D83 — same fault.

The Vaillant D.83 fault code means: your boiler is providing a status update to show it is currently heating up the water for your taps.. 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: Burner start up in hot water mode

What causes the Vaillant D.83 fault?

This code appears when the boiler detects a demand for hot water and begins the ignition sequence to heat it. It is not actually a fault, but a status message indicating that the internal burner is firing up to provide water for your taps or shower. Once the water reaches the required temperature, the code will usually change or disappear.

DIY fix possible

This fault may be fixable without an engineer. Check your manual first.

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Vaillant models that show the D.83 fault code

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

Source

Vaillant D.83 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 27 April 2026