D.022 Low

Vaillant D.022 Fault Code

Also written as D022 — same fault.

The Vaillant D.022 fault code means: your boiler is correctly registering that you have turned on a hot water tap and is beginning the process of heating the water for you.. 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: Hot water requirement (via C1/C2, impeller or APC)

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.022 fault code

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

Source

Vaillant D.022 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