Lexi2009

Hi, I have a 2009 ES300 with Nav. I recently bought this used at the Lexus dealership in NY. I can't understand why the Parking Assist alarm goes off each time I am at a certain intersection. This intersection is a T junction with no shrubbery or other obsticles anywhere near my car, and yet the car starts beeping when I aproach and wait at the intersection to turn. I have had no other false alrms with Parking Assist except at this intersection. What could be causing this? Thanks in advance for your input!