BoilerFaultCodesViessmann 76:1 Fault Code
Also written as 761 — same fault.
The Viessmann 76:1 fault code means: your boiler is having difficulty communicating with its internal smart connection module, usually meaning there is a minor electronic glitch or a connection has come loose.. It appears on 5 Viessmann models in our database.
Technical description: With LON communication module; automatic recognition
What causes the Viessmann 76:1 fault?
This fault occurs when the boiler's internal brain loses touch with the communication module that allows it to talk to other smart devices or controls. It is usually caused by a loose connection following a recent service, or a small electronic failure where the internal wiring has become insecure. In some cases, it simply means the communication board has failed and needs replacing to restore the data link.
DIY fix possible
Switch off the boiler's power supply for 30 secondsSwitch the power back on and wait for the system to rebootPress the Reset button on the control panel
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Gas Safe Register →Viessmann models that show the 76:1 fault code
Click a model for the full fault code list and model-specific repair notes.
Source
Viessmann 76:1 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