Blind Spot Assist uses a radar sensor system to monitor the areas on both sides of your vehicle. It begins to work at speeds of approximately 20 mph (30 km/h). A warning display in the exterior mirrors draws your attention to detected vehicles in the monitored area. If you then indicate a turn towards that side before changing lanes, you will also receive visual and audible collision warnings. The Blind Spot Assist monitoring system uses sensors in the rear bumper.

WARNING  
Blind Spot Assist is only an aid designed to assist driving. It may fail to detect some vehicles and is no substitute for attentive driving.
Blind Spot Assist cannot detect road and traffic conditions. It may fail to detect narrow vehicles, such as motorcycles or bicycles, or may only detect them too late.
Monitoring may be affected by dirty sensors, strong spray or poor visibility caused by snow, rain or mist, for example. In this case, vehicles are detected late or not at all.
Always pay attention to traffic conditions and your surroundings. Otherwise, you may fail to recognize dangers in time, cause an accident and injure yourself and others.

USA only:

This device has been approved by the FCC as a “Vehicular Radar System”. The radar sensor is intended for use in an automotive radar system only. Removal, tampering, or altering of the device will void any warranties, and is not permitted by the FCC. Do not tamper with, alter, or use in any non-approved way.

Any unauthorized modification to this device could void the user’s authority to operate the equipment.

For Blind Spot Assist to assist you when driving, the radar sensor system must be activated and operational.