BoilerFaultCodesViessmann 450 Fault Code
The Viessmann 450 fault code means: your boiler's computer has encountered an internal error while trying to process its operating software, causing the system to stop working.. It appears on 1 Viessmann model in our database.
Technical description: Error in scheduled program run monitoring
DIY fix possible
Locate the reset button or menu option on the boiler control panelPress and hold the reset button for at least 3 secondsWait for the boiler to restart and monitor if the code clears
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Viessmann models that show the 450 fault code
Click a model for the full fault code list and model-specific repair notes.
Source
Viessmann 450 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