What does the Viessmann Vitodens 111-W F86 fault code mean?
The F86 fault code indicates a problem with the Domestic Hot Water (DHW) status, which may prevent the boiler from supplying hot water. This issue can arise from various components malfunctioning or failing to communicate properly.
Common Causes
- Faulty DHW Sensor: A malfunctioning sensor may not accurately detect the temperature of the water, leading to incorrect readings and the F86 fault.
- Wiring Issues: Damaged or loose wiring connections between the DHW components and the boiler control unit can disrupt communication, triggering the fault code.
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 DIY repairs could be dangerous.
Estimated Repair Cost (2026 UK Prices)
The estimated repair cost for resolving the F86 fault could range from £150 to £300, depending on whether a sensor replacement or wiring repair is needed. This estimate includes parts and labour for a qualified engineer.