The 17 year-old, who has name suppression, was last month sentenced at the High Court in Auckland.
to two years of intensive supervision and 200 hours of community work.
One of the conditions of the supervision order was that she should not access the internet.
A probation officer told the court on Friday the teenager had accessed social media website Facebook using a mobile phone. The Facebook page was under a fake name.
Crown prosecutor William Fotherby told the court her computer could be fitted with software that will record her online activity.
Justice Ellis told the teenager she would be sent to jail if she did not comply with the supervision order. She is due back in court next week.
Her 19-year-old former boyfriend, Johann Daubeck, has previous convictions for sexual offending and was sentenced to prison for seven years. He will serve a minimum sentence of at least four years.