What does the Viessmann Vitodens 100-W F65 fault code mean?
The F65 fault code on the Viessmann Vitodens 100-W indicates a problem with the heating curve, which affects the boiler’s ability to adjust the water temperature based on the outside temperature. This can lead to inefficient heating and potential comfort issues within the property.
Common Causes
- Incorrect Heating Curve Settings: The heating curve may be set incorrectly in the boiler’s control settings, leading to inadequate temperature adjustments.
- Sensor Malfunction: A faulty outdoor temperature sensor may provide inaccurate readings, causing the boiler to miscalculate the required heating output.
Can I fix it myself? (DIY)
It is recommended to call a Gas Safe Engineer to diagnose and resolve this issue, as it involves adjustments to the boiler’s settings and potentially replacing faulty components.
Estimated Repair Cost (2026 UK Prices)
The estimated repair cost for addressing the F65 fault code is around £150 to £250, depending on whether it requires recalibration of settings or replacement of a faulty sensor.