You can have your doors unlock, your boot open, or even your car start will the push of a button on a key fob, or a key remote. Having only one key fob when more than one person uses the car, however, may cause issues. To resolve this issue, you can make a copy of a key fob--a process that requires little to no mechanical aptitude. There are two types of key fobs--a switch-style key fob and a programmable key fob. You can program both fobs in no more than one half hour.
Open the backs of both the existing and the new key fob by removing the screw(s) on the back of the remote. Count the little white switch tabs on the inside of both. If the second key fob has fewer (or more) switches than the original, it is not the right fob for your vehicle. Key fobs must be vehicle-specific to set the proper frequency for your particular remote.
Examine the position of the switches one-by-one on the existing key fob. Set the switches on the second key fob exactly as they appear on the existing key fob. There should be two to three settings on each switch. Double check for accuracy.
Seal both key fobs back together and test the newly programmed key fob. If the key fob does not work, open the cases back up and check for accuracy again. If the secondary key fob is switched identical to the first one, then it should work.
Turn the ignition key to the "Accessories" position. This is the step right before you start your car.
Aim the existing remote to the car and depress the "Unlock" button for five to 10 seconds. While pressing the "Unlock" button, also press the "Panic" or "Alarm" button and hold for one second.
Release both buttons simultaneously. If you have completed the above mentioned steps correctly, your vehicle will chime or beep to let you know that you have entered "Remote Programming Mode."
Aim the secondary remote at your vehicle and press any button within 30 seconds of the chime or beep. Your vehicle will again chime or beep to let you now that it is leaving "Remote Programming Mode."
Test both the primary and secondary remotes. Repeat these steps if the process does not work the first time. Take the vehicle to a dealership if the process does not work.
Some vehicles do not have switch inserts inside of them. They are factory programmed remotes, which may require a car dealership to program. The programming of a remote usually costs between £48 and £55 (as of September 2010).
Do not change any of the switches on the primary remote. Changing these switches will render your initial remote fob useless on your vehicle.