D.058 Low

Vaillant D.058 Fault Code

Also written as D058 — same fault.

The Vaillant D.058 fault code means: your boiler is currently detecting that the water coming from your solar heating system is not hot enough, so it is temporarily heating it further to ensure you have hot water.. It appears on 7 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: Solarcircuitpost-heating

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.058 fault code

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

Source

Vaillant D.058 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