D.58 Low

Vaillant D.58 Fault Code

Also written as D58 — same fault.

The Vaillant D.58 fault code means: your boiler has paused its own water heating because it detects that your solar panels have already provided enough heat for your hot water cylinder.. It appears on 24 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: Activation of solar reheating

What causes the Vaillant D.58 fault?

This occurs when your solar thermal system has successfully heated the water in your cylinder to the required temperature. The boiler is monitoring the cylinder sensor and has intelligently decided to pause its own gas burner to avoid wasting energy and overheating the water. It is a sign that your system is working efficiently by prioritizing free renewable energy over gas.

This status is most frequently seen during spring and summer months when there is sufficient sunlight to allow your solar panels to handle the full water heating load.

DIY fix possible

No action is required as this is an advisory status message rather than a functional fault.Check your solar thermal controller to confirm it is operating as expected.Wait for the solar heat input to decrease, at which point the boiler will resume normal operation if needed.

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Vaillant models that show the D.58 fault code

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

Source

Vaillant D.58 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