Abstract: The detector is a watertight unit that is easily secured on or through a vehicle bumper, or other extremity, to sense and give warning of obstacles in the path of the vehicle. Warning is given by either head on or oblique contact of a detector probe with the interference. Advance time of such warning may be altered by changing the length of the probe. The detector contains an electrical switch, closed by probe displacement, to activate the available vehicle horn. Utilizing independently powered equipment provides the warning quickly and without the need of significant and/or prolonged relative motion between the vehicle and the obstacle. The invention is readily adaptable for use on fixed objects to provide warning of vehicle approach.