Viessmann D6 Error ❲ORIGINAL • 2026❳

: A faulty or disconnected sensor (such as the outdoor temperature sensor or a flow sensor) sending an "open circuit" signal to the control unit.

Do not attempt DIY beyond the basic reset if: viessmann d6 error

The KM-BUS is a two-wire system (typically red and white or yellow). If any single device on that bus—such as the outdoor temperature sensor, mixing valve actuator, cylinder temperature sensor, or extension module—fails, it can “pull down” the entire bus voltage, causing D6. : A faulty or disconnected sensor (such as

When a D6 error appears, the boiler's internal computer has detected that it cannot "talk" to a component or is receiving an invalid signal. This usually results in: When a D6 error appears, the boiler's internal

Sometimes the fault is a temporary logic glitch.

A: No. F4 usually means ignition failure; A7 means gas valve fault. D6 is strictly a communication bus error.