Ducati Monster 796 Workshop Manual page 241

System components
The stepper motor simultaneously controls two by-pass ports having an air flow capacity of around 6 kg/h.
The by-pass ports with adjuster screws are present because it is necessary to balance the air flow to the two cylinders.
In order to compensate for the quantity of supplementary air supplied by the stepper motor and consequently deliver the
correct amount of fuel, the ECU converts the stepper motor steps into angular degrees of the throttle: this system means
that opening the stepper motor is equivalent to opening the throttle.
Note
The influence of the stepper motor air flow is present to approximately 30° throttle angle; no correction is required for
greater angles.
The opening of the stepper motor opening is controlled by 2 strategies:
Strategy 1) controlled solely by engine temperature (stepper motor opening/closing is determined by engine temperature
alone).
Strategy 2) controlled by engine temperature and status. This strategy is applied only in the engine starting phase; the
system determines a quantity of steps, to be added to those of the previous strategy, which are immediately decreased
to zero, in accordance with the number of engine cycles, once the system has detected that the engine has started.
Lambda sensor
The Lambda sensor, positioned on the exhaust pipe, transmits information to the ECU on the amount of oxygen present in
the exhaust fumes. With this information the ECU can maintain optimal control over the fuel-air mixture.
The outer surface of the sensor element in zirconium dioxide is in direct contact with the exhaust gas, while the inner
surface is in contact with the atmosphere. Both surfaces are coated with a thin layer of platinum. Oxygen in ionic form
travels through the ceramic layer and charges the platinum layer electrostatically so that the platinum acts as an
electrode: the electrical signal generated is carried on the sensor output cable.
The zirconium dioxide element becomes permeable to oxygen ions at a temperature of around 300 °C.
When the oxygen concentration is different on the two sensor surfaces, a voltage is generated thanks to the special
physical properties of the zirconium dioxide. With a lean mixture the signal voltage is low, while with a rich mixture it is
high.