BoilerFaultCodesVaillant d.72 Fault Code
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 22 Vaillant models in our database.
Technical description: Pump over run (for loading warmstart) (ecoMAX 800)
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.
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.
- Atmomax Repair: £0-80
- ecoMAX Repair: £90-220
- ecoMAX 613 Repair: £120-250
- ecoMAX 618 Repair: £120-250
- ecoMAX 622 Repair: £120-250
- ecoMAX 635 Repair: £120-250
- ecoMAX 824E Repair: £120-250
- ecoMAX 828E Repair: £120-250
- Ecomax Condensing 600/800 series
- ecoMAX System 612 Repair: £120-250
- ecoTEC Repair: £0-80
- ecoTEC 65kW
- ecoTEC plus aquaPLUS
- ecoTEC Pro / ecoTEC Plus
- Thermocompact
- Turbomax 824/828
- Turbomax Plus
- Turbomax Plus 824/828E
- Turbomax Plus 828
- Turbomax Plus 828 E
- Turbomax Plus VUW 242E
- Turbomax Plus VUW 242EH
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.
- Vaillant ecoMAX manual (PDF)
- Vaillant ecoMAX System 612 manual (PDF)
- Vaillant ecoMAX 824E manual (PDF)
Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed 7 July 2026