BoilerFaultCodesViessmann F.346 Fault Code
Also written as F346 — same fault.
The Viessmann F.346 fault code means: your boiler is struggling to automatically adjust its fuel-to-air balance, so it has safely shut down to prevent inefficient or unsafe burning.. It appears on 4 Viessmann models in our database.
Technical description: Automatic calibration of the combustion controller error
Engineer required
This fault requires a Gas Safe registered engineer. Do not attempt gas-related repairs yourself.
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Viessmann models that show the F.346 fault code
Click a model for the full fault code list and model-specific repair notes.
Source
Viessmann F.346 fault code information on this page is sourced and cross-checked against the official Viessmann service / installation manuals for each affected model.
- Viessmann Vitodens 100-W WB1A manual (PDF)
- Viessmann Vitodens 200-W B2HF System manual (PDF)
- Viessmann Vitodens 200-W B2KF Combi manual (PDF)
Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed 7 July 2026