What does the Viessmann Vitodens 200-W F99 fault code mean?
The F99 fault code on the Viessmann Vitodens 200-W indicates a problem with user retention, which typically relates to issues with the control board or user interface. This fault can prevent the boiler from operating correctly and may require a reset or further investigation.
Common Causes
- Control Board Failure: A malfunction in the control board can disrupt communication between the user interface and the boiler, leading to the F99 error.
- User Interface Issues: Problems with the user interface, such as a faulty display or buttons, can also trigger this fault code.
Can I fix it myself? (DIY)
It is recommended to call a Gas Safe Engineer for this issue, as it involves electrical components that can be dangerous to handle without proper training. Attempting to fix it yourself may void any warranties and could pose safety risks.
Estimated Repair Cost (2026 UK Prices)
The estimated repair cost for resolving the F99 fault code could range from £150 to £300, depending on whether the control board or user interface needs replacement. This cost reflects the complexity of the repair and the need for professional expertise.