Unexpected system behavior

A situation that requires explaining to the driver may occur if the function limits of the ACC system are reached. Such situations are described in the following:

• Great differences in speed between the vehicle and the vehicle in front cannot be regulated by the system. In this case, a brake intervention on the part of the driver is necessary.
• The Active Cruise Control does not react to stationary traffic obstructions or oncoming traffic.
• The distance control is limited by the detection range of the radar sensors: in the event that vehicles cut in very closely and quickly in front of the vehicle, intervention on the part of the driver can be necessary.
• The leading vehicle may be lost when cornering due to the limited side field of view of the radar sensors. In this case, the acceleration to the set speed is briefly suppressed. Reason: this will prevent the vehicle from accelerating too close to the vehicle ahead, which is possibly only briefly not being monitored.
• If the ACC sensor is "blinded", for example if covered by snow, the ACC switches off. A Check Control message is output to the driver. The ACC can be reactivated after cleaning the radar sensors.
  NOTE: Damage to the ACC sensor cover can cause the ACC sensor to malfunction.
• If ASC or DSC intervene for longer periods (with critical coefficients of friction), ACC switches off.
• Rain, fog and snow absorb the radar beams. This can significantly reduce the range of ACC. In extreme cases, ACC can no longer be used.
• Brows of hills and depressions may obstruct detection, causing objects to be lost.
• In very rare cases, objects can be sensed with incorrect measured values (usually the angle). For example, due to reflection of the radar beams from tunnel walls and guarding rails.
• At very low temperatures (below minus 20 deg C), the ACC sensor may only attain operating readiness after some delay. In this case, the ACC function cannot be activated. This is indicated in the instrument panel by "- - -".