Each Ford Explorer has its own factory keyless entry code ( if equipped ) It has the capability of "remembering" a 2nd personal entry code if you wish to program a 2nd code in to the system (Helpfull)
The security codes for each radio are unique. There will be a card with the number in the original manual supplied with the vehicle when purchased new. There you will also find the procedure for unlocking the radio. If you do not have the original card containing the code you may go to your nearest Mercedes Benz dealer with I.d and proof of ownership of the vehicle and they will be able to get the code and tell you the procedure.
In order to get the security code for Opel Astra you will need to order an additional key code. Each code is unique, so no one has the same code.
The factory code is unique to your vehicle
The radio unit will need the security code If you disconnect the battery from your vehicle. The radio will reset, thinking it was stolen out of the car, and will require the security code before it will work again.
You will have to go to the dealer to get the reset code and instructions. It will be unique to your particular radio.
It is a unique code.
The factory code is unique to each vehicle
Unless you set a security code and remember what it is the dealer is your only option because of security system radios are vehicle specific when installed at factory vehicle needs to be hooked up ro comp at dealer and reset (approx $100)
http://www.truthorfiction.com/rumors/c/carlock.htm
The security code is 0000
lost security code
When you purchased your vehicle, you should have received a card that lists the four-digit security code for the radio. If you do not have this you have to call the dealer and give them the serial number of the radio to get the code.