How much does it cost to fix Vaillant error code d.72?

Typical repair cost for the Vaillant d.72 fault is £90-220 including labour.

d.72 Low

Vaillant d.72 Fault Code

Q: What does the Vaillant d.72 fault code mean?

Your boiler's pump is running longer than it should to cool down the system after heating water, usually because a sensor has detected a temperature imbalance.

Also written as D72 — same fault.

The Vaillant d.72 fault code means: your boiler's pump is running longer than it should to cool down the system after heating water, usually because a sensor has detected a temperature imbalance.. It appears on 14 Vaillant models in our database.

Technical description: Hot-water pump over run

What causes the Vaillant d.72 fault?

This fault occurs when the boiler detects an unusual temperature difference between the water leaving the unit and the water coming back in. The most common cause is a faulty or drifting temperature sensor providing inaccurate readings, which trick the boiler into thinking it needs to run the pump longer than necessary to cool down. In some cases, it can also be a sign that water is not circulating as freely as it should through the heat exchanger.

Typical repair cost £90-220 (including labour)

DIY fix possible

Check that all radiator valves are open to ensure good water flowTurn the boiler off at the main switch, wait 30 seconds, and turn it back onCheck the system pressure is between 1.0 and 1.5 bar

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Vaillant models that show the d.72 fault code

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

Source

Vaillant d.72 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