Viessmann D6 Error -

A: Yes. A shorted outdoor sensor (common after lightning storms) can drop the entire bus voltage. Disconnect it—if D6 disappears, replace the sensor.

If the extension module (EA1) itself is faulty, it will need a professional replacement. viessmann d6 error

The boiler will refuse to fire until the triggering device is cleared. 🛠️ How to Fix the D6 Error 1. Check Connected External Devices A: Yes

Call a Viessmann-trained technician immediately if: viessmann d6 error