BoilerFaultCodesVaillant d.41 Fault Code
Also written as D41 — same fault.
The Vaillant d.41 fault code means: your boiler is displaying the current temperature of the water returning from your radiators rather than showing an error; this is an informational status code and not a fault.. It appears on 32 Vaillant models in our database.
Technical description: Heating return temperature
DIY fix possible
Check if the display returns to the main temperature screen after a few momentsPress the 'back' or 'menu' button to exit the diagnostic information if you accidentally selected itNo action is required as this is a normal reading of the system's return water temperature
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Vaillant models that show the d.41 fault code
Click a model for the full fault code list and model-specific repair notes.
- Atmomax
- ecoFIT Pure 418
- ecoFIT Pure 425
- ecoFIT Pure 435
- ecoFIT Pure 825 Repair: £120-220
- ecoFIT Pure 830 Repair: £150-250
- ecoFIT Pure 835
- ecoMAX
- ecoMAX 613
- ecoMAX 618
- ecoMAX 622
- ecoMAX 635
- Ecomax Condensing 600/800 series
- ecoMAX System 612
- ecoTEC 65kW Repair: £150-250
- ecoTEC Plus 615
- ecoTEC Plus 620
- ecoTEC Plus 625
- ecoTEC Plus 635
- ecoTEC Plus 840
- ecoTEC plus aquaPLUS
- ecoTEC sustain
- Home Combi Repair: £120-220
- Home System
- 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.41 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