How do you change the key code on a 2002 ford explorer?

On the keyless entry pad on the driver's door, you can change a personal code, but the factory code can't be erased To erase an existing personal code, enter the factory code and within 5 seconds press and hold the 1/2 button for at least 6 seconds - the factory code will still work. ---------------------------------------------------------------------------------------------------------- Choose a new personal code that doesn't use 5 digits in sequence or use the same button 5 times. Enter the factory code Within 5 seconds press the 1/2 button Within 5 seconds of pressing the 1/2 button enter your new 5 digit code, pressing each digit within 5 seconds of the previous digit. You can use the factory code or your personal code to unlock/lock doors