Active Steering Assist is country-dependent and only available for vehicles with the Driving Assistance Package.
Active Steering Assist is operational at speeds up to 210 km/h and helps you to stay in the centre of the lane by means of moderate steering interventions. It uses the vehicle in front and the lane markings as a reference depending on the driven speed.
When the system is actively steering, the 
symbol is shown in green in the multifunction display.
If the detection of lane markings and vehicles ahead is impaired, Active Steering Assist switches to passive mode. The system provides no support in this case. During the transition from active to passive status, the symbol is shown as enlarged and flashes yellow. Once the system is passive, the symbol is shown as grey in the multifunction display.
The driver is required to keep their hands on the steering wheel at all times and be able to intervene at any time to correct the course of the vehicle and keep it in lane. The driver must expect a change from active to passive mode or vice versa at any time.
If the system reaches a system limitation or the driver has not steered the vehicle for a considerable period of time or has removed their hands from the steering wheel, the system will, depending on the situation, alert the driver either with a visual warning or a visual and acoustic warning. Display 
appears in the multifunction display.
If the driver does not steer the vehicle over a long period, or has not taken hold of the steering wheel, a repeated warning tone sounds in addition to the visual warning message (depending on the country).
The driver steers the vehicle.
The driver presses a steering wheel button or operates Touch Control.
Active Steering Assist is only an aid. The driver is responsible for the distance to the vehicle in front, for vehicle speed, for braking in good time and for staying in lane. Before changing lanes, the driver must make sure that the neighbouring lane is free (glance over the shoulder).
Active Steering Assist has a limited steering torque for lateral guidance. In some cases, the steering intervention is not sufficient to keep the vehicle in the lane or to drive past exits.
In snow, rain, fog, heavy spray, if there is glare, direct sunlight, greatly varying light conditions, reflections or strong shadows on the carriageway.
Insufficient road illumination.
The windscreen in the area of the camera is dirty, misted up, damaged or covered.
Absence of lane markings, or several unclear lane markings, or if the markings change rapidly.
The distance to the vehicle in front is too small and the lane markings thus cannot be detected.
The road is narrow and winding.
Obstacles on the lane or projecting out into the lane.
On tight bends, junctions, toll stations, roundabouts and when turning.
When towing a trailer.
When actively changing lane without switching on the turn signal.
When the tyre pressure is too low.
If the system limitations of Active Steering Assist are reached there is no guarantee that the system will remain active or will keep the vehicle in lane.
A malfunction in the detection of lane markings and objects can occur.
This could cause unexpected steering intervention.