12. Turbo control
WARNING: This page is about a different car, the 2001 Saab 9-3. However, it is still accessible from the selected car via links, so may be relevant.
If the requested air mass/combustion is too high to be handled by the throttle control alone, the turbo control will take over. The excess is converted to a PWM, which controls the charge air control valve. The absolute atmospheric pressure is used to correct this conversion.