What Is A Car Key Transponder Chip And How Does It Work?

A transponder – short for ‘transmitter and responder’ – has been commonplace in a car’s ignition key since the mid-1990s. Originally introduced as an elegant solution to tackle rising theft rates, a car key transponder ensures that every car has a unique code that is needed to start the ignition. Automotive technology has developed at pace in the past three decades, so the fact that transponders are still used by many major OEMs is a testament to their effectiveness. But what is a car key transponder, and how does it work?

What Is A Transponder Key For A Car?

A transponder is essentially an electronic chip, which has a fine wire coil around it to transmit and receive electromagnetic signals. The chip itself is similar to the memory storage in your computer or smartphone in that it doesn’t require a constant source of power to retain memory. This is known as non-volatile memory. The kind of transponder used in a car key is known as a Magnetic Coupled Transponder system. These systems don’t require constant electricity, and therefore don’t have their own power source. A car key transponder operates in a radio frequency range (around 125kHz), meaning that it can penetrate plastic or rubber, which is why we’re able to place it within the bow of the key. Because they don’t have their own power source, car key transponders only have a range of between 1-15cm.

How Does A Car Key Transponder Work?

As well as a transponder chip in the key, modern cars also have an induction coil that is fitted around the ignition barrel. When the key is inserted into the barrel and turned to the ‘on’ position, the induction coil sends out a pulse of electromagnetic energy. The wire coil around the transponder chip absorbs this energy, which powers the chip and causes it to emit a signal, which is the key’s identification code. This signal is sent back to the induction coil, which reads the code. If the code is recognised by the vehicle’s on-board computer, it will commence the car’s start procedure and allow it to run. In recent years transponder systems have been developed to use cryptographic or rolling codes so that the code cannot be copied from the vehicle’s computer.

Where Can You Buy A Transponder?

Owing to the importance of a transponder to a car’s security, it is important you buy transponders from a reputable and trusted source, such as Advanced Keys. Advanced Keys offers a comprehensive range of transponder chips, which work with several key programming systems, including The Diagnostic Box TDB1000, which we can also supply. Our knowledgeable staff, same-day shipping* and competitive prices make Advanced Keys the best place to buy a transponder.

* Orders paid for by credit or debit card before 15:00 Monday to Thursday or 12:00 Friday will be posted out on the same day where possible.

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