Collision warning system* - camera sensor limitations

"Collision Warning with Auto Brake and Cyclist and Pedestrian Detection" is an aid to assist the driver when there is a risk of colliding with a pedestrian, bicycle or vehicle in front that are stationary or moving in the same direction.

The function uses the car's camera sensor, which has certain limitations.

The car’s camera sensor is also used - as well as by Collision Warning with Auto Brake - by the functions:


Keep the windscreen surface in front of the camera sensor free from ice, snow, mist and dirt.

Do not stick or attach anything to the windscreen in front of the camera sensor as this may reduce effectiveness or cause one or more of the systems dependent on the camera to stop working.

The camera sensors have limitations similar to the human eye, i.e. they "see" worse in darkness, heavy snowfall or rain and in thick fog for example. Under such conditions the functions of camera-dependent systems could be significantly reduced or temporarily disengaged.

Strong oncoming light, reflections in the carriageway, snow or ice on the road surface, dirty road surfaces or unclear lane markings could also significantly reduce camera sensor function when it is used to scan the carriageway and detect pedestrians and other vehicles.

The field of vision of the camera sensor is limited, which is why pedestrians, cyclists and vehicles cannot be detected in some situations, or they are detected later than anticipated.

During very high temperatures the camera is temporarily switched off for about 15 minutes after the engine is started in order to protect camera functionality.

Fault tracing and action

If the display shows the message Windscreen sensors blocked See manual then this means that the camera sensor is blocked and cannot detect pedestrians, cyclists, vehicles or road markings in front of the car.

At the same time, this means that - besides Collision Warning with Auto Brake - the Automatic main/dipped beam dimming, Road Sign Information, Driver Alert Control and Lane Keeping Aid functions will not have full functionality either.

The following table presents possible causes for a message being shown along with the appropriate action.

The windscreen surface in front of the camera is dirty or covered with ice or snow.Clean the windscreen surface in front of the camera from dirt, ice and snow.
Thick fog, heavy rain or snow means that the camera does not work sufficiently well.No action. At times the camera does not work during heavy rain or snowfall.
The windscreen surface in front of the camera has been cleaned but the message remains.Wait. It may take several minutes for the camera to measure the visibility.
Dirt has appeared between the inside of the windscreen and the camera.Visit a workshop to have the windscreen inside the camera cover cleaned - an authorised Volvo workshop is recommended.
  1. * Option/accessory.

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