BoilerFaultCodesVaillant D.96 Fault Code
Also written as D96 — same fault.
The Vaillant D.96 fault code means: your boiler has reverted to its original factory settings and needs its specific configuration data entered to work correctly with your heating system.. It appears on 12 Vaillant models in our database.
Technical description: Factory setting
What causes the Vaillant D.96 fault?
This fault occurs when the boiler's internal computer loses the specific identity code that tells it which model it is. It most commonly happens after a power surge or when a major electronic component, such as the circuit board, has been replaced but not yet programmed. Without this configuration data, the boiler stays in a 'factory default' state and won't ignite for safety reasons.
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.96 fault code
Click a model for the full fault code list and model-specific repair notes.
- Atmomax Repair: £90-180
- ecoFIT Pure 418 Repair: £120-250
- ecoFIT Pure 425 Repair: £100-£180
- ecoFIT Pure 435 Repair: £120-200
- ecoFIT Pure 825
- ecoFIT Pure 830 Repair: £100-200
- ecoFIT Pure 835 Repair: £90-150
- ecoTEC Repair: £80-160
- ecoTEC 65kW Repair: £120-200
- ecoTEC Pro / ecoTEC Plus
- ecoTEC sustain Repair: £120-200
- Home Combi Repair: £100-200
Source
Vaillant D.96 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 835 manual (PDF)
- Vaillant ecoTEC manual (PDF)
- Vaillant ecoTEC 65kW manual (PDF)
Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed 7 July 2026