Pope Francis has struggled to resolve the problem as the steady drip of scandal corrodes the church's authority but fresh cases surface regularly against a background of sharp divisions in Rome over the issue.
The Vatican said an investigation by the Archbishop of Los Angeles had found suspicions about Salazar's behavior to be "credible."
A letter from the archbishop, Jose H. Gomez, said that in 2005 he had been "made aware of an allegation against Bishop Salazar of misconduct with a minor" during the 1990s when he was serving as a parish priest.
The allegations were investigated by the police but not prosecuted, Gomez said, adding that since Salazar was a bishop when the allegations were made, he had passed the issue to the Vatican "which conducted an investigation and imposed certain precautionary measures."
Salazar, 69, "consistently denied any wrongdoing," Gomez said, and after obtaining permission from Rome, he had put the matter in the hands of the archdiocese's "independent Clergy Misconduct Oversight Board."
"The Board found the allegation to be credible and I submitted its findings and recommendations along with my own votum to the Holy See to make its final determination as to Bishop Salazar's status," he said. "These decisions have been made out of deep concern for the healing and reconciliation of abuse victims and for the good of the Church's mission. Let us continue to stay close to the victim-survivors of abuse, through our prayer and our actions."
Earlier this year a U.S. grand jury report found credible allegations against more than 300 predator priests and identified over 1,000 victims in decades of child sex abuse covered up by the Catholic Church in Pennsylvania. As a result of the church cover-up, almost every instance of abuse was too old to be prosecuted, the report said.
The victims "were brushed aside, in every part of the state, by church leaders who preferred to protect the abusers and their institution above all," it said.
The problem is clearly a major one — 14,500 people applied for compensation through an Irish government scheme for those abused at juvenile facilities run by religious groups between 1936 and 1970.
Observers said the trip was also notable for revealing how far the church's standing had been damaged by the scandal and how Ireland, traditionally a bastion of the faith, now appeared much less willing to give the Vatican the benefit of the doubt.
Pope Francis has organized a conference in February in the Vatican, with bishops urged as part of preparations to "reach out and visit with victims of sexual abuse... to learn first hand the suffering that they have endured."