.The function can also take streetlights into account. Main beam is reactivated when the camera sensor no longer sees any oncoming vehicles or vehicles ahead.
The function can start while driving in the dark when the car's speed is approx. 20 km/h (approx. 12 mph) or higher.
If active main beam is deactivated while main beam is on, the lighting is immediately reset to dipped beam.
When active main beam is activated, the symbol 
illuminates with a white glow in the driver display.
When main beam is activated, the symbol shines blue. This also applies for LED headlamps if the main beam is partially dimmed, i.e. if the light beam shines with slightly more than dipped beam.
Car with LED1 headlamps*
If the active main beam has the on/off functionality2 then the lighting returns to main beam about a second after the camera sensor no longer detects the headlamp beams from oncoming traffic or the rear lights from vehicles in front.
If the active main beam has adaptive functionality2 then, unlike what happens during conventional dimming, the light beam continues to illuminate with main beam on both sides of oncoming traffic or vehicles ahead - only the part of the light beam that points directly to the vehicle is dimmed.
The lighting returns to full main beam about a second after the camera sensor no longer detects the headlamp beams from oncoming traffic or the rear lights from vehicles in front.
Limitations for active main beam
The camera sensor on which the function is based has limitations.
If this symbol is shown in the driver display, together with the message Active High Beam Temporarily unavailable, then switching between main and dipped beam must be performed manually. The rotating ring on the stalk switch can still be in the position. The symbol extinguishes when these message are shown.
The same applies if this symbol is shown together with the message Windscreen sensor Sensor blocked, see Owner's manual.
Active main beam may be temporarily unavailable e.g. in situations with dense fog or heavy rain. When active main beam becomes available again, or the windscreen sensors are no longer blocked, the message goes out and the symbol illuminates.
Warning
Active main beam is an aid for using the optimum beam pattern when conditions are favourable.
The driver always bears responsibility for manually switching between main and dipped beam when traffic situations or weather conditions so require.