What does the Viessmann Vitodens 100-W F43 fault code mean?
The F43 fault code on the Viessmann Vitodens 100-W indicates a problem with the gas supply to the boiler. This can prevent the boiler from igniting and functioning properly, leading to heating and hot water issues.
Common Causes
- Blocked Gas Supply: A blockage in the gas line can restrict the flow of gas to the boiler, causing the F43 fault.
- Gas Valve Malfunction: A faulty gas valve may not open or close correctly, preventing gas from reaching the burner.
Can I fix it myself? (DIY)
It is strongly advised to call a Gas Safe Engineer for any issues related to gas supply or electrical components. Attempting to fix these problems yourself can be dangerous and is not recommended.
Estimated Repair Cost (2026 UK Prices)
The estimated repair cost for resolving the F43 fault could range from £150 to £300, depending on whether the issue is a simple blockage or requires replacement of the gas valve.