D.13 High

Vaillant D.13 Fault Code

Also written as D13 — same fault.

The Vaillant D.13 fault code means: your boiler is having trouble moving hot water through the internal pipes, which usually means the circulation pump cannot start or is stuck.. It appears on 28 Vaillant models in our database.

Call an engineer soon

Book a Gas Safe engineer within 24 to 48 hours. Your boiler may be unsafe or could break down completely if left.

Technical description: Hot water circulation pump

What causes the Vaillant D.13 fault?

This fault occurs when the boiler's internal pump fails to spin, meaning heated water cannot be moved toward your radiators or hot water tank. The most common reason is that the pump has become physically seized by a buildup of sludge or debris, or the electrical components inside the pump have reached the end of their lifespan.

This issue is frequently seen in autumn when the heating is turned back on for the first time after being idle all summer, which allows debris to settle and seize the pump.

Typical repair cost £220-450 (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.13 fault code

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

Source

Vaillant D.13 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