BoilerFaultCodesVaillant P.02 Fault Code
Also written as P02 — same fault.
The Vaillant P.02 fault code means: your boiler is performing a routine self-diagnostic purge or testing phase and is not currently experiencing a breakdown.. It appears on 11 Vaillant models in our database.
Technical description: Minimum load: After successful ignition, the product is operated at minimum heat input.
What causes the Vaillant P.02 fault?
This code appears because your boiler is running a brief self-test to ensure the system is stable at its lowest power setting. It occurs automatically during the startup sequence to verify that the internal components are functioning correctly before ramping up the heat. It is a sign that the boiler's internal computer is performing its standard safety and efficiency checks.
DIY fix possible
Wait for the boiler to complete its 15-minute test cycleDo not turn the boiler off, as it will reset the timerOnce the cycle finishes, the screen will return to its normal display
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Vaillant models that show the P.02 fault code
Click a model for the full fault code list and model-specific repair notes.
Source
Vaillant P.02 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 Home Combi 35 manual (PDF)
Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed 31 August 2026