She said: "I need him to come home. He's running scared.
"I know what he's done to this family is horrific and what they're going through, but he is my son and as a mum myself I'm worried about where he is and what his state of mind is."
McAteer said she felt "numb" after seeing a CCTV image released by police after the crash of her son.
She said she contacted police after seeing the photo. She said: "I was just thinking of that poor woman and little girl".
She added: "I don't condone this and if I could go back in time I would."
The mother of 4, who has another son, 18, and two daughters aged 11 and 20, said she would usually hear from McAteer every day, but had not heard from him since before the crash.
She said: "I'm a mum to children and I don't know how I would feel if this happened to them.
"What I'm feeling is probably a fraction of what she is."
She added: "This is a nightmare but my nightmare is not half as bad as it is for that family."
Dean Brennan, 27, appeared at Liverpool Magistrates' Court today charged with assisting an offender, theft of a motor vehicle and the aggravating offence of allowing oneself to be carried within a stolen vehicle.
A third man, aged 23 and from Prescot, was arrested on suspicion of being carried in a stolen vehicle but later released pending further inquiries.
Violet-Grace's mother, Rebecca Youens, paid tribute to her "brave baby girl" after she died in hospital.
"My beautiful baby girl passed away in my arms on 25/03/2017 at 23:38," she said in a Facebook post.
"Thank you for all your well wishes ... she was just too poorly.
"However, my brave baby girl saved two lives by donating her kidneys and pancreas.
"I am truly heartbroken but proud of my little fighter."
A fundraising website set up in memory of the youngster has raised more than £16,000.
- PA, AAP
