Ultrasonic park assist sensors in the front or rear bumper fascia allow the park assist system to locate and identify the proximity of nearby obstacles. These sensors each generate ultrasonic sound pulses when triggered by the park assist module, then signal the module when an echo of the reflected sound pulses is received. The detection distance range from the front or rear of the vehicle is about 0.3 meters (11.8 inches) to about 1.5 meters (59.1 inches), and the detection height range from the ground is about 0.2 meters (7.8 inches) to about 0.8 meters (31 inches). The detection area extends somewhat around both sides (corners) of the vehicle. I haven't heard of any issues with the proximity sensors not being able to detect obstacles farther than 18in.
