S
Stephen RobinsonAug 30, 2025
What to do if Viessmann Vitodens 100-W shows fault F4?
- DDaisy AguilarAug 31, 2025
If your Viessmann Boiler displays fault code F4, indicating no flame signal, you should inspect the ionisation electrode and its connecting cables. Also, verify the gas pressure, gas train, ignition, ignition module, and condensate drain. After these checks, press the "Reset" button.