BoilerFaultCodesVaillant 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 29 Vaillant models in our database.
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.
Engineer required
This fault requires a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.
Find a Gas Safe engineer
Search the official register for a qualified engineer in your area.
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A cover plan would handle faults like D.13: no call-out fees, no surprise bills.
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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.
- Atmomax Repair: £220-£450
- ecoFIT Pure 418
- ecoFIT Pure 425
- ecoFIT Pure 435
- ecoFIT Pure 825 Repair: £150-300
- ecoFIT Pure 830 Repair: £150-350
- ecoFIT Pure 835
- ecoMAX Repair: £150-300
- ecoMAX 613 Repair: £120-250
- ecoMAX 618 Repair: £120-250
- ecoMAX 622 Repair: £120-250
- ecoMAX 635 Repair: £150-300
- ecoMAX 824E Repair: £120-250
- ecoMAX 828E Repair: £120-250
- Ecomax Condensing 600/800 series Repair: £150-300
- ecoMAX System 612 Repair: £150-300
- ecoTEC Repair: £220-450
- ecoTEC 65kW Repair: £180-350
- ecoTEC Plus 615
- ecoTEC Plus 620
- ecoTEC Plus 625
- ecoTEC Plus 630
- ecoTEC Plus 635
- ecoTEC Plus 840
- ecoTEC plus aquaPLUS Repair: £120-280
- ecoTEC Pro / ecoTEC Plus Repair: £150-300
- ecoTEC sustain
- Home Combi Repair: £150-350
- Home System
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.
- Vaillant ecoFIT Pure 835 manual (PDF)
- Vaillant ecoMAX manual (PDF)
- Vaillant ecoMAX System 612 manual (PDF)
Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed 7 July 2026