Sources say Locklear successfully completed the program and, as one person familiar with the situation says, "She's doing great."
Although she went to rehab after she was arrested for hit-and-run in April, sources say her decision to seek treatment had nothing to do with the incident.
TMZ broke the story ... someone mowed down a "no parking" sign near Heather's gated community in Westlake Village, CA. Cops determined the car -- registered to Heather and her ex, Richie Sambora -- struck the sign, but authorities could not determine who was driving the vehicle.
Prosecutors rejected the case because of insufficient evidence.