What does the Viessmann Vitodens 200-W F35 fault code mean?
The F35 fault code on the Viessmann Vitodens 200-W indicates a malfunction with the domestic hot water (DHW) sensor. This issue can lead to improper temperature readings and affect the boiler’s ability to provide hot water efficiently.
Common Causes
- Faulty DHW Sensor: The sensor may be defective or damaged, leading to inaccurate temperature readings.
- Wiring Issues: Damaged or loose wiring connections to the DHW sensor can cause communication failures between the sensor and the boiler control unit.
Can I fix it myself? (DIY)
It is recommended to call a Gas Safe Engineer to diagnose and repair this issue, as it involves electrical components and gas safety regulations. Attempting to fix it yourself could pose safety risks.
Estimated Repair Cost (2026 UK Prices)
The estimated cost for replacing a faulty DHW sensor on a Viessmann Vitodens 200-W is approximately £150 to £200. This includes the cost of the part and labour, reflecting the complexity of the repair and the need for a qualified technician.