BoilerFaultCodesVaillant d.81 Fault Code
Also written as D81 — same fault.
The Vaillant d.81 fault code means: this code is simply an information display showing the total number of hours your boiler has spent actively producing hot water, rather than a fault indicating a problem.. It appears on 26 Vaillant models in our database.
Technical description: Running time in hot water handling mode
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.81 fault code
Click a model for the full fault code list and model-specific repair notes.
- ecoFIT Pure 418
- ecoFIT Pure 425
- ecoFIT Pure 825
- ecoFIT Pure 830
- ecoFIT Pure 835
- ecoMAX
- ecoMAX 613
- ecoMAX 618
- ecoMAX 622
- ecoMAX 635
- ecoMAX 824/2 E
- ecoMAX 828/2 E
- ecoMAX 835 E
- Ecomax Condensing 600/800 series
- ecoTEC plus VU GB 656/4-5 A
- ecoTEC sustain
- Home Combi 25
- Home Combi 30
- Home Combi 35
- 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.81 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 425 manual (PDF)
- Vaillant ecoFIT Pure 835 manual (PDF)
- Vaillant Ecomax Condensing 600/800 series manual (PDF)
Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed 31 August 2026