Electro-Hydraulic Solenoid
The solenoid regulates the amount of power steering assist for the servotronic system. It contains a needle valve that can restrict oil flow. When current is applied, the needle valve closes against spring pressure to restrict the oil flow.
With maximum current applied, the valve is closed. This is the condition of the valve for slow speed driving and parking.
Without current applied, the needle valve is held open by spring pressure. This is the condition of the solenoid during higher driving speeds.