What to do if my Vaillant Controller displays an 'F. Boiler fault' code?
- DDeanna BoltonAug 3, 2025
If your Vaillant Controller displays 'F. Boiler fault' followed by a specific fault code (e.g., F.33), it indicates a boiler fault. To resolve this, first reset the boiler by selecting 'Reset' and then confirming with 'Yes'. If the fault message continues to appear, inform a qualified technician.