What does the Viessmann Vitodens 100-W F55 fault code mean?
The F55 fault code indicates a malfunction with the domestic hot water (DHW) sensor in the Viessmann Vitodens 100-W boiler. This issue can prevent the boiler from properly regulating water temperature for hot water supply.
Common Causes
- Faulty DHW Sensor: The sensor may be defective or damaged, leading to incorrect temperature readings.
- Wiring Issues: Damaged or loose wiring connections to the DHW sensor can disrupt its functionality.
Can I fix it myself? (DIY)
It is recommended to call a Gas Safe Engineer to diagnose and repair this issue, as it involves gas and electrical components that require professional expertise.
Estimated Repair Cost (2026 UK Prices)
The estimated repair cost for replacing the DHW sensor is around £150 to £250, including parts and labour. This cost reflects the price of the sensor and the professional service required for installation.