How much does it cost to fix Vaillant error code d.46?

Typical repair cost for the Vaillant d.46 fault is £120-220 including labour.

d.46 Low

Vaillant d.46 Fault Code

Q: What does the Vaillant d.46 fault code mean?

Your boiler is struggling to communicate with the external weather sensor attached to your home, which means it cannot automatically adjust your heating based on the outside temperature.

Also written as D46 — same fault.

The Vaillant d.46 fault code means: your boiler is struggling to communicate with the external weather sensor attached to your home, which means it cannot automatically adjust your heating based on the outside temperature.. It appears on 9 Vaillant models in our database.

Technical description: Outside–temperature correction (only when VRC 410s is fitted)

Typical repair cost £120-220 (including labour)

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.46 fault code

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

Source

Vaillant d.46 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