The couple, a 17-year-old boy and his 18-year-old passenger, died when their Mazda crashed into a Hyundai i30 on Long Valley Road, Gemmells on Tuesday about 4.40pm.
The driver of the Hyundai, a 31-year-old woman, received only minor injuries.
She was transported to Mount Barker Hospital for treatment.
The road was closed until just before midnight.
The death of the two teens, believed to be high school sweethearts, takes South Australia’s 2018 road toll to 68.
It was 87 at the same time in 2017.