BoilerFaultCodesViessmann 97:0 Fault Code
Also written as 970 — same fault.
The Viessmann 97:0 fault code means: your boiler is notifying you that it is using the reading from the outdoor temperature sensor to manage its operation, which may be a temporary update or a minor communication check.. It appears on 5 Viessmann models in our database.
Technical description: The outside temperature of the sensor connected to the control unit is utilised internally
What causes the Viessmann 97:0 fault?
This code is triggered when the boiler's internal computer updates how it processes information from the outdoor weather sensor. It is essentially a background synchronization task where the system re-calibrates the temperature data to ensure your heating runs efficiently. It rarely indicates a physical breakdown and is usually just the software confirming its settings are correct.
DIY fix possible
Check the outdoor sensor is not covered by snow, ice, or debrisMonitor the boiler display to see if the message clears automaticallyRestart the boiler once to see if the advisory code clears
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Gas Safe Register →Viessmann models that show the 97:0 fault code
Click a model for the full fault code list and model-specific repair notes.
Source
Viessmann 97:0 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