BoilerFaultCodesVaillant d.02 Fault Code
Also written as D02 — same fault.
The Vaillant d.02 fault code means: your boiler has reached its target temperature and is taking a short rest to prevent it from turning on and off too frequently, which protects the internal components.. It appears on 22 Vaillant models in our database.
Technical description: Burner anti-cycling time in heating mode
DIY fix possible
Check that your room thermostat is set to the desired temperature.Ensure all radiator valves (TRVs) are open in the rooms you are using.Wait 10 to 15 minutes for the countdown to end and the boiler to restart automatically.
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Gas Safe Register →Vaillant models that show the d.02 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.02 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