What does the Viessmann Vitodens 111-W F98 fault code mean?
The F98 fault code on the Viessmann Vitodens 111-W indicates a problem with the domestic hot water (DHW) update process. This typically suggests an issue with the control system or sensor that manages the DHW temperature and flow.
Common Causes
- Faulty DHW Sensor: A malfunctioning sensor may fail to provide accurate temperature readings, leading to the F98 error.
- Control Board Issue: A fault in the control board can disrupt the communication between components, affecting the DHW update process.
Can I fix it myself? (DIY)
It is recommended to call a Gas Safe Engineer for this issue, as it involves gas and electrical components that require professional expertise. Attempting to fix it yourself could be dangerous.
Estimated Repair Cost (2026 UK Prices)
The estimated repair cost for addressing the F98 fault could range from £150 to £300, depending on whether the DHW sensor or control board needs replacement. The cost reflects the complexity of diagnosing and replacing these components.