Transponder keys are devices designed to transmit a radio signal from a handheld device to a remote receiver. They're most commonly used to unlock and start vehicles, though they're also used in things like gate openers and keyless entry systems. Each one is programmed to only start a specific vehicle, to reduce the possibility of theft. There are a number of ways to bypass transponders, however, most of which can be done with inexpensive equipment.
Technology
In vehicular-use transponder keys, introduced in 1995, the transmitter unit consists of a small microchip in the plastic part of a key. The microchip has a unique serial number, which is set during its initial programming. When a person wants to unlock or start a car, the chip sends a request to the car for it to validate the serial number and turn off the engine immobilizers. If the car doesn’t recognize the number, it will remain locked and immobilized. A key that has not been programmed can still turn the engine over, but it won't be able to start it, since the immobilizers will still be activated.
Transponder keys are available for many different cars, but are more common in new or high-end models. Though cars can be retrofitted for transponder systems, it's often expensive, since it involves creating or reprogramming their electrical system and making a new key. Locksmiths may be able to do this, but a person might have to go to an auto dealer, since they usually don't like to release their programming information, possibly for fear of theft.
Advantages and Disadvantages
The technology involved in programming keys to specific vehicles has led many manufacturers and insurance companies to consider cars with transponder keys to be virtually theft-proof. There are many reports, however, of thieves finding ways around the system, sometimes simply by towing the car away, or by using a bypassing machine. The perception of being theft-proof has caused problems for some owners, as it can be more difficult to convince an insurance company if the car actually is stolen.
Bypassing
Keeping at least two transponder keys on hand is generally a good idea, since replacements are generally very expensive. If replacements are needed, they can usually be made by an auto dealer or locksmith, but this can be expensive. There are also kits that can bypass transponders as well as tutorials for bypassing them with electrical relays and wiring. Additionally, some people get a new plain key cut for the ignition and tape the transponder key on the inside of the steering column so that it is close enough to turn off the engine immobilizers, and the person can start the car with a plain key.
It is possible for drivers to program their own blank keys, but the process varies by vehicle make and model. There are many model-specific instructions posted on the Internet, but owners may have to experiment to find on that works. If all else fails, they can try contacting the manufacturer to see if they give out programming instructions or buy a new key.
Other Uses of the Technology
Besides being used to start cars, transponder technology can also be found in a variety of other applications. These include wireless alarm keys, garage or gate opening remote controls, and wireless house-entry systems. More recent advances in the technology have led to the development of keyless entry and starting systems. With these systems, the signal is continually sent out from the fob, and as it's in range of the receiver, the doors will be unlocked and car can be started with a push-button ignition. If the key is removed from the active range of the vehicle, the doors will lock automatically and an immobilizer system will be activated.