There’s a hidden danger when you sell your vehicle…take it to a repair shop…reach the end of a lease…or return a rental car. The danger is in leaving detailed personal information in the auto’s onboard computer, making you vulnerable to cybertheft.

For several years, infotainment systems in many vehicles have let you connect, or “pair,” your smartphone wirelessly via Bluetooth or through a USB cable. Problem: As drivers increasingly use car infotainment systems to send texts and e-mail, browse the Internet, log into ­mobile apps, get directions and even open garage doors, a vehicle’s computer might store much of the data, which can be accessed easily by a tech-savvy thief.

What to do: When you sell a vehicle or return a leased one, wipe personal data from the computer. Many vehicles have a factory-reset option that returns the settings and data to their original state. Check the owner’s manual or contact a dealer. Otherwise, delete information manually. Go to the infotainment system’s main menu. Navigate to the list of paired devices, and follow the instructions to delete yours. If you used the vehicle’s navigation system, clear your location history…and clear any garage-door codes.

For rental cars, doing a factory reset might violate a rental agreement requirement to not modify the vehicle’s functionality. Instead, manually delete paired devices and location history. Ask rental-car personnel to walk you through the steps if you need help. If you visit a mechanic you don’t trust not to snoop, delete your paired devices temporarily and reload your data when you get the vehicle back.

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