On some Bluetooth enabled devices, the default pairing code is 0000 or 1234. On other devices, the pairing code is listed on the documentation that came with the device.
Also known as a "passkey," a pairing code is a numerical code that allows a Bluetooth-enabled device to connect to a computer. Pairing codes are used primarily for security reasons, ensuring that a computer connects to the intended device, and not any other device that is within the computer's Bluetooth range.
When the Bluetooth of a computer and a device are turned on, both devices recognizes each other by "exchanging passkeys" or by "pairing." In Windows OS, this process of pairing passkeys enables users to determine the right device with which to connect. For some devices, the user may be prompted to type the passkey before both devices consummate the pairing process.
In some instances, the pairing code on the device may be lost or forgotten. Computers running Windows OS can use its "Add Bluetooth Device Wizard" feature to resolve this problem. This feature will either generate a pairing code or create one for the user.
For devices running iOS, a pairing code that is entered incorrectly six times in a row will lock out the device from pairing with a computer. This problem can be solved by syncing the device with a computer, erasing the contents of the device (including the pairing code) and then restoring the device from backup.