BoilerFaultCodesViessmann F.377 Fault Code
Also written as F377 — same fault.
The Viessmann F.377 fault code means: the boiler is struggling to automatically adjust its internal burner settings during a routine check, often due to an unstable gas supply or a worn ignition component.. It appears on 4 Viessmann models in our database.
Technical description: Post-processing ionisation calibration: stabilisation conditions not reached
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.377 fault code
Click a model for the full fault code list and model-specific repair notes.
Source
Viessmann F.377 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