Nicholas John Hamauei was taken into custody Tuesday by Montgomery County Sheriff's deputies, who were patrolling the parking lot on Westridge Road.
According to the Montgomery County Sheriff's Office, Hamauei and the teen appeared to be having sex inside of the suspect's car.
When the suspect spotted deputies, he attempted to drive off but was stopped a short time later.
Deputies said a search of the vehicle allegedly led them to find marijuana inside.
Hamauei was booked into the Montgomery County Jail on a $100,000 bond. He is charged with felony sexual assault of a child and marijuana possession.