Transponder keys are car keys that have a transponder chip in them. The word “transponder” is derived for the words “transmitter” and “responder.” The transponder chip embedded in the car key gives off a signal that communicates with the car receiver. It disarms the vehicle’s immobilizer when the transponder car key is used to start the engine. This serves as an additional security feature against car theft. The car won’t be able to start until the specific signal is sent to the car’s transceiver from the transponder chip in the keys.
There are two types of transponder keys. The zero bitted transponder key and the encrypted transponder key. The basic difference between these two types of transponder keys lies in their inscriptions. While the zero bitted keys are set up in such a way that they can be cloned because they are not given any preset inscriptions. The encrypted keys have a preset random inscription that is specific for the car.
Transponder key programming is not for everyone. Some BMW’s do not come with a transceiver and require just a plain metal key to be able to start them. BMW cars that come with a transceiver need transponder key programming. Any attempt to do away with the programming will be putting your car at risk.
BMW car keys make use of this security feature. The keys do not come enabled, so you will have to either call an auto locksmith to program it or try to do it yourself. Attempting to do it yourself requires that you have one working key and one key that requires programming.
The first step is usually to hold the keys close to the rear view mirror, that is where the sensors are located. Then you get into the car with both keys and close all the windows and doors. Put the working key into the ignition and turn it on, turn it off immediately and remove the working key from the ignition. Within 3 seconds, put the key you want to program into the ignition and also turn it on, after which you turn it off. Bring out the key you want to program, press and hold your unlock button. While holding the button (unlock), press the lock button (the one with the BMW logo) three times and subsequently release the unlock button. By now, you should hear the doors lock and unlock.
Alternatively, you could put the key in the ignition and turn it on five times very quickly. Then remove the key, and hold the unlock button then press the lock button three times, after which you release the unlock button. Then turn on the ignition to finalize. If you have any other keys to program, you can repeat the process for each of them.