Vitotronic 300 Low

Viessmann Vitotronic 300 Fault Code

Also written as VITOTRONIC300 — same fault.

The Viessmann Vitotronic 300 fault code means: your boiler has switched to a protective mode because the outdoor temperature has dropped to freezing, causing it to run the heating pump continuously to prevent pipes from freezing.. It appears on 5 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: Activates after 0°C / 32°F outdoor temperature

DIY fix possible

Check that your outdoor sensor is not covered by snow or debrisEnsure your thermostat is set to your desired room temperatureWait for the outdoor temperature to rise above freezing for the notification to clear automatically

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Viessmann models that show the Vitotronic 300 fault code

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

Source

Viessmann Vitotronic 300 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 27 April 2026