BoilerFaultCodesVaillant d.05 Fault Code
Also written as D05 — same fault.
The Vaillant d.05 fault code means: your boiler is simply displaying the target temperature it is currently trying to reach for your heating, which is a normal status message rather than an actual fault.. It appears on 22 Vaillant models in our database.
Technical description: Determined heating flow set target temperature: Current value
DIY fix possible
Press the 'Back' or 'Menu' button to return to the main displayCheck that your external thermostat is calling for heat if you want the temperature to increaseNo action is required as this is an information code, not an error
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Gas Safe Register →Vaillant models that show the d.05 fault code
Click a model for the full fault code list and model-specific repair notes.
- aquaPLUS
- ecoFIT pure
- ecoFIT Pure 412
- ecoFIT Pure 418
- ecoFIT Pure 425
- ecoFIT Pure 435
- ecoFIT Pure 835
- ecoTEC plus
- ecoTEC Plus 615
- ecoTEC Plus 620
- ecoTEC Plus 625
- ecoTEC Plus 630
- ecoTEC Plus 635
- ecoTEC Plus 65
- ecoTEC Plus 832
- ecoTEC Plus 836
- ecoTEC Plus 840
- ecoTEC Plus 938
- ecoTEC plus Aquaplus
- ecoTEC plus System
- ecoTEC sustain
- Home System
Source
Vaillant d.05 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