Bradford Crown Court heard that the former England and Sunderland footballer had kissed and sexually touched the girl in his Range Rover
Former England footballer Adam Johnson has lost his appeal against his conviction for child sex offences, according to his sister.
The ex-Sunderland player is serving six years in prison for engaging in sexual activity with a 15-year-old fan.
His sister Faye posted a message on Twitter, which said: "Absolutely devastated that the single judge has rejected my brother's appeal against sentence and conviction.
"But I can assure every supporter that it has made me stronger and I will never give up."
The trial of the 28-year-old winger at Bradford Crown Court heard that he had kissed and sexually touched the girl in his Range Rover, in a secluded spot in County Durham.
Faye Johnson, who set up an appeal on Facebook, went on to say: "Also my appeal page has been temporarily removed but will be back up and running very soon with the link to my website.
"Thank you to everyone for your continued support daily it means a lot and keeps me going."
At the trial, Judge Jonathan Rose said he was satisfied the girl, who was besotted with Johnson, had suffered "severe psychological harm" and that the footballer had taken advantage of "a young teenager's adoration of a successful celebrity".
Johnson was also arrested for being in possession of extreme pornography, and pre-trial hearings heard that police found medicines in a safe when he was arrested indicating he may have been suffering from sexually transmitted infections.
He had won 12 England caps and previously played for Manchester City. His contract with Sunderland was cancelled when he admitted one count of grooming and one of sexual activity with a child at the start of his trial.
He had denied two further charges, but was convicted of one of them in March this year.
After the trial his teenage victim issued a statement saying: "The last 12 months have been horrendous and there have been times when I've wanted to hide away from the world. There have been times I haven't felt able to face people/
"There have been times when I've tried not to show people how upset I am, but sometimes it hasn't been possible and I'd just cry. I've felt so broken."