BoilerFaultCodesViessmann 95 Fault Code
The Viessmann 95 fault code means: your boiler has lost communication with your smart thermostat or heating controller and cannot receive instructions to heat your home.. It appears on 1 Viessmann model in our database.
Technical description: OpenTherm remote control not connected
DIY fix possible
Check that your wall-mounted thermostat is switched on and has working batteries.Ensure any wireless receiver plugged into or near the boiler has a power light on.Try restarting your internet router if your OpenTherm controller relies on a bridge or hub connection.
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Viessmann models that show the 95 fault code
Click a model for the full fault code list and model-specific repair notes.
Source
Viessmann 95 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