BoilerFaultCodesVaillant D.80 Fault Code
Also written as D80 — same fault.
The Vaillant D.80 fault code means: this is not a fault, but simply an informational status screen showing the total number of hours your boiler has spent in heating mode.. It appears on 6 Vaillant models in our database.
Technical description: Operating hours heating
What causes the Vaillant D.80 fault?
This is an informational status code rather than a mechanical failure. It is triggered when a user or engineer navigates to the diagnostic menu to see how much work the boiler has done specifically for central heating. It simply records the cumulative time the burner has been active to provide a history of the appliance's usage.
This code may be checked more frequently during the winter months when homeowners are more likely to monitor their heating usage and energy consumption.
DIY fix possible
Press the 'Back' or 'i' button to exit the diagnostic menuNo action is required as this is a normal status message
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Gas Safe Register →Vaillant models that show the D.80 fault code
Click a model for the full fault code list and model-specific repair notes.
Source
Vaillant D.80 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