Traffic was affected after a vehicle reportedly came off the road and hit a tree near the bottom of Macquarie Pass on Sunday.
According to Ambulance NSW, no one was injured in the incident.
The incident is believed to have occurred about three-quarters of the way down Macquarie Pass, on the Illawarra Highway near Clover Hill Road about 12.55pm.
Highway traffic was affected in both directions, but appears to have returned to normal conditions.
Emergency services attended the scene.
Meanwhile, traffic has also been affected at Mount Pleasant, after a bus breakdown on the M1 (Mount Ousley Road) approaching Clive Bissell Drive.
One of three northbound lanes is closed.