Transponder keys have been around since 1995 and have slowly become a staple option in most new cars. A transponder key is a device that can open and/or start a car through the use of a radio signal. Transponder keys are not limited to working with vehicles, and they can also be used for any key-less entry. The transponder is programmed to open or start only one vehicle (or door, gate, etc.).

How does a transponder key work?

The transponder key really consists of two parts: the transmitter and the responder (transponder is a combination of these two words). The transmitter is made up of a microchip that is capable of sending a signal to the responder. The microchip is in the key portion of the transponder. It is associated with a serial number during manufacturing, and when the microchip sends a request to the responder, the responder must recognize the serial number in order for it to respond. If a microchip attempts to communicate with the responder and the serial number isn’t recognized, the responder will remain locked. If the number can be validated, however, the locks will be released and the car will open or the ignition start.

The two main varieties of transponder keys are those used for remote entry and those that are used similarly to traditional keys, just with the added protection of specificity for your car’s ignition. Remote transponder keys are now sold with almost every car as well, and are the devices often attached to the key or key chain that can open or start your car from across the parking lot. Other transponder keys are used just like regular keys, except that when inserted in the ignition they send a radio signal to your car that must be recognized in order for your car to start.

Most cars made after 1995 come equipped with transponder keys, although they are usually only found in high-end models before that. Transponder systems can be added to a car that doesn’t already have one, however it can be a bit expensive as the electrical system of the car has to be reprogrammed.

Pros and Cons

At first cars with transponder keys were thought to be immune to theft, as they would only turn on with the programmed key. However, thieves have found ways to get around the transponder system. This can involve drastic measures like towing the car, then using it for parts. Many thieves have grown savvy, however, and learned how to bypass the transponder key. In some cases, the thief will actually replace the transponder technology, which will allow them access to the ignition. They also can create programmed keys that weren’t authorized or disarm the car’s immobilizer through other means.

However, although thieves have figured out ways around transponder keys, they still are a safer alternative to traditional keys. The work that has to be done to start a car that has a transponder system can sometimes make stealing them not seem worthwhile. It requires a far greater level of expertise than stealing a car with a traditional system.