While some initial checks can be performed by a homeowner, most D6 repairs require a Gas Safe registered engineer due to the involvement of the gas burner and internal electrical components. Viessmann Fault Code Checker
It often signifies that the fan speed is too high or too low at startup, preventing the ignition sequence from beginning safely. viessmann d6 error
In some configurations, it may indicate a fault at the DE1 connection on the external safety device adapter. Common Causes of a D6 Fault Several underlying issues can trigger this lockout: While some initial checks can be performed by
The precise definition of a D6 error varies slightly across the Viessmann product range: viessmann d6 error