Tesla points to a small gear in the parking brake that was built improperly by a third-party supplier as the culprit for the issue. If this gear were to break, it would mean that the parking brake would be unable to be disengaged, preventing the car from moving. There have been no reports of any injuries due to this defect, nor of the parking brake failing to hold, and it doesn't affect the car's regular braking systems. Tesla says that only a small amount – two to five percent – of the gears used in its vehicles built in that period have the flaw.
The problem came to the automaker's attention after a number of customers received alerts that their parking brakes needed servicing, or their parking brake wouldn't disengage. Telsa traced the problem back to a batch of brakes supplied from Brembo. It will be filing the recall with NHTSA, but is sending out letters to customers and assuring them their cars are safe to use in the meantime.
According to TechCrunch, the fix takes less than 45 minutes. It's a lot of cars to recall for a flaw that affects a but a small portion, and doesn't threaten safety. Tesla likes to get ahead of these sort of things, though, and says it wants to make sure no issues arise for its customers.