BoilerFaultCodesViessmann 544 Fault Code
The Viessmann 544 fault code means: your boiler has lost the signal from a sensor for a secondary heating zone, so it has safely shut off that specific part of your home's heating to prevent overheating.. It appears on 1 Viessmann model in our database.
Technical description: Emergency function operating mode is activated for heating circuit 2: Mixer closes. Heating circuit pump is operational. Lead break, flow temperature sensor, heating circuit 2 with mixer
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 544 fault code
Click a model for the full fault code list and model-specific repair notes.
Source
Viessmann 544 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