Karen Swedberg was arrested after a Vacaville police officer received a report that she was involved in a sexual relationship with the boy, according to police.
The officer learned that the relationship was allegedly still ongoing in Millbrae, where Millbrae police had also received a report about the relationship.
Swedberg was located and detained at her home in Millbrae Friday, according to Vacaville police.
Detectives determined that Swedberg was aware of the boy's age, and she was transported back to Solano County and booked into jail without incident, police said.
Anyone with information about the case is asked to call Detective Patrick Cowan at (707) 469-6621.