Viessmann D6 Error →

A generally points to a communication or sensor issue within the system's extension modules, though the exact meaning can vary slightly depending on whether you have a boiler or a heat pump. 🛠️ Common Causes & Troubleshooting

Close filling loop taps completely; bleed radiators to drop pressure to 1.2 bar. Failed or uncharged expansion vessel viessmann d6 error

If your Viessmann boiler is showing a D6 error, it usually indicates a flame failure or ignition problem. That can mean the burner is not lighting, the flame is being lost during operation, or the ignition sequence is interrupted. Below is a concise guide to diagnosing, troubleshooting, and when to call a pro. A generally points to a communication or sensor

The boiler usually continues to run (normal operation), but the specific function controlled by that expansion input is compromised. Heat Pump Specifics: On some heat pump models like the Vitocal 200-S , D6 can specifically refer to a flow switch (Strömungswächter) fault , indicating insufficient water flow through the unit. Viessmann Climate Solutions Community Common Triggers for D6 That can mean the burner is not lighting,