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What Is a Transponder Key and Why They’re Used as Car Keys

what is a transponder key
Last Updated on January 22, 2023
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Gone are the days of flat metal car keys. Now we have remote controls, key fobs, and even chipped transponder keys. Knowing what they are, how they work, and other factors can save you from a headache if you lose yours or need to get a key replacement.

A transponder key is a car ignition key that has an RFID chip installed into it. This chip sends a low-level signal to the remote receiver (immobilizer) when you attempt to start up the vehicle. The RFID chip and immobilizer are programmed with the same unique identification code; without it, the car will not run. This greatly reduces the chances of car theft.

This article will outline and detail everything there is to know about transponder chip keys. It will cover, what they are, how they work, their benefits, how to tell if you have one, how to copy them, the difference between transponder and non-transponder car keys, and much more.

Let's get to it!

What Is a Transponder Key?

transponder key rfid chips

A transponder key is a car key that has an additional anti-theft security measure implemented into it. This is accomplished by installing a radio frequency identification microchip (also referred to as an RFID) inside the key's plastic head section.

How Does a Transponder Key Work?

A transponder key works by transmitting a low-level signal that is accepted by a remote receiver called an immobilizer system. This system is located either in or near your ignition system and will search for the signal from the key during the startup sequence of a vehicle.

This RFID chip has a unique digital serial number that is associated with it and the vehicle. When you try to start a car's ignition system by turning the key, the serial number programmed into the remote receiver and the chip must correlate to each other; otherwise, the car will not start.

How Secure Are Transponder Keys?

A key with a transponder provides a higher level of security for your vehicle than a traditional non-transponder key in two ways.

  1. If the ignition system is physically broken, it cannot be bypassed even if the ignition is turned by another tool or key.
  2. If there is any attempt to "hot-wire" the vehicle, it also won't start. The digital identification number programmed to the key and remote receiver are practically unique. If the built-in immobilizer system does not register this unique ID, the car will not start.

It should be noted that immobilizer systems work in various ways, but the principle of a transponder key sending its unique signal to the remote receiver is the same.

No matter what immobilizer system you have, the car won't be able to run without the correct transponder key. If you attempt to start your car with the incorrect key, the following will likely occur.

  • The engine may not start at all
  • The engine may start, but no fuel will be injected into the motor; thus, the car will never run
  • The engine may start, but it will shut off after a specific period of time

How Do I Know if My Car Key Is a Transponder Key?

transponder key rfid

In general, most cars that have been built within the last 20 years (and some even earlier than that) have been manufactured with a transponder chip inside the key. So if your car was manufactured in 2000 or onward from that year, the chances are very good that it most likely your key has a transponder.

Furthermore, if your vehicle was manufactured after 2010, the chances are very high that it uses a transponder key. Overall, almost all new cars have a transponder key; gone are the days of simple mechanical keys.

Another way to tell if your car key is a transponder key is in the way it is built. In the design of the key (the plastic section), there will typically be a bow. This means that the plastic section is thicker than how standard metal flat keys used to be. However, note that with every passing year, technology progresses, and you now get transponder keys that are becoming thinner.

How Do I Make Sure My Car Key Is a Transponder Key?

The first thing you can do is check your vehicle's make and model. Once you have that information, there are a few avenues you can pursue to determine whether your car key is a transponder key or not;

  • You can call one of your local car dealerships and ask them if your make and model are built with a transponder key
  • You can call a local auto parts store or auto locksmith and ask them if your car's make and model is built with a transponder key
  • You can search online and search via Google or visit the website TransponderKey.com and choose the make and model of your vehicle

What Are the Benefits of a Transponder Key?

We touched on the fact that transponder keys offer an additional layer of security to help thwart car thieves, which is the most beneficial aspect of it and the primary reason for its invention.

Besides offering more in the way of security, a transponder key offers two additional benefits such as:

  • They offer better functionality
  • They are simple to use

Transponder Keys Offer Better Functionality

In terms of functionality, a transponder key is able to combine locking or accessing your vehicle with other tasks. For example, most new transponder keys will arm the alarm system when you lock up the vehicle.

However, take note that a transponder key is different from a car key remote which works to lock your car by way of pushing its buttons. This is similar to a key fob that does not necessarily have a key attached to it.

Transponder Keys Are Easy to Use

Transponder keys are simple to use and do not require you to push any buttons in most instances. Some immobilizer systems will have you press one or multiple buttons in order for you to either unlock the car or turn off the immobilizer.

Copying a Transponder Key (Transponder Key Replacement)

copying a transponder key duplicates

On some occasions, you will need to make a copy of a transponder key or get a replacement made. If this is the case, there are some factors that you will need to consider.

Can I Copy a Transponder Key?

The first factor to consider before determining whether you can copy a transponder key is that transponders come in two variations. These are namely;

  • Fixed (encrypted) transponders
  • Clonable transponders

Fixed Transponders

Fixed transponders are designed with device programming or onboard programming in mind. These transponders will be connected to the vehicle's diagnostics port, and they cannot be cloned.

Clonable Transponders

These transponders are designed to allow a new unique ID to be programmed onto the RFID chip. It does this by using an already existing compatible transponder. Thus, copying a transponder key can only be done if you have a duplicate in your possession.

Take note that most cars today come with two transponder keys and a third that is programmable by the car. This third key is simple enough that you can take it to any professional locksmith to get copied, but you could program it yourself if the car allows you to.

The instructions will be detailed in the owner's manual if that car's make and model allows you to program the key yourself. Otherwise, you can look online because many sources show you how to do this for various makes and models of cars. YouTube is a blessing.

If your car does not allow you to program it yourself, then you will have to contact a dealership, car locksmith, or use another service. Personally, I favor using a trusted locksmith over a dealership; it's significantly cheaper (which we'll cover in a moment).

Where Can I Get a Copy Made and How Much Does It Cost?

The price to copy a transponder key will vary depending on where you go and your specific vehicle.

Copying a single key could run hundreds of dollars if you intend to go through a certified car dealership. They likely charge you approximately $75 for the transponder portion of the key and then about $160 to replace the key. If you are looking at a laser-cut key, then you are looking at a staggering $250.

If you want to go to a locksmith, they will charge you between $20 and $30 to replace an entire transponder key with the RFID chip included.

Take into consideration that these are the prices of the keys, and in some situations, you will have to pay the additional labor costs.

You also have the option to take it to local stores like AutoZone, Walmart, and Home Depot. The price to copy a key at these stores is pretty inexpensive and will cost you around $3 to $6. You also have the luxury of purchasing transponder key fobs from them for a price that ranges between $15 and $90. These transponder fobs allow you to program the chip yourself if the make and model of your car permit you to do so.

How to Copy a Transponder Key?

Here we will detail how to copy a transponder key in a step-by-step fashion. We have outlined the procedure previously, but the following is a direct how-to method.

  1. Firstly, you will need to check if the make and model of your car allow you to program a transponder key.
  2. If it does not, then you will have to get it done at a certified dealer, professional locksmith, or store that provides the service.
  3. If the make and model of your car do allow you to program it yourself, you will need to acquire a transponder key blank from a locksmith, auto parts store, or online.
  4. If you do have a spare key but need it cut or cloned, then you should take it to a professional locksmith or one of the local stores that can do it for you.
  5. Additionally, if you need to purchase a transponder key fob, then you should consider purchasing it at a local store.
  6. The only thing left to do if you intend to program the transponder key yourself is to refer to your owner's manual on what the procedure entails or check how to do it online.


In this guide, we discovered that a transponder key is a key that relays a radio frequency signal to the immobilizer in your car when you go through the ignition startup process. It adds an extra layer of security due to the RFID chip that is installed in it and has a couple of other additional benefits.

Typically, cars that have been built in the past twenty years will have a transponder key, and a car will be sold with two already programmed keys and a third programmable one.

You are able to copy transponder keys but not ones that are fixed or encrypted.

If you need to copy one, you will need to have a copy of the key and take it to a certified dealer or locksmith or do it yourself. If you don't have a duplicate, you will need to order it from a dealer.

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