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

Typical repair cost for the Vaillant d.46 fault is £100-200 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 its outdoor weather sensor, so it is currently ignoring local temperature readings and defaulting to standard operations.

Also written as D46 — same fault.

The Vaillant d.46 fault code means: your boiler is struggling to communicate with its outdoor weather sensor, so it is currently ignoring local temperature readings and defaulting to standard operations.. It appears on 1 Vaillant model in our database.

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

Typical repair cost £100-200 (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.

Ecomax Condensing 600/800 series Repair: £100-200

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 27 April 2026