F.299 Low

Viessmann F.299 Fault Code

Also written as F299 — same fault.

The Viessmann F.299 fault code means: your boiler's internal clock has lost its settings, likely due to a temporary power cut, and simply needs to be reset to the correct date and time.. It appears on 4 Viessmann models in our database.

Monitor it

This is a minor fault. Keep an eye on it and mention it at your next annual boiler service. Reset the boiler and see if it clears.

Technical description: Real time clock setting incorrect

DIY fix possible

Locate the display panel on your boilerAccess the settings menu using the buttons providedUpdate the date and time to the current settings and save

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Viessmann models that show the F.299 fault code

Click a model for the full fault code list and model-specific repair notes.

Source

Viessmann F.299 fault code information on this page is sourced and cross-checked against the official Viessmann service / installation manuals for each affected model.

Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed 7 July 2026