How a transponder key works

These days, transponder keys are the norm in new vehicles. They make it much more difficult for a thief to steal your car. Even though it’s expensive, no doubt, it’s worth the peace of mind it affords you.

If you have a transponder key ~ also known as a transponder “chip” ~ then you already know how much easier it is to use than a regular key. These specialized keys are ignition keys you can use to enter and leave your car without a hitch. You can unlock the car door without sticking the key in the lock mechanism; you can open your trunk remotely; you can activate and deactivate your car alarm; and, with some vehicles, you can even start it up remotely!

A chip inside the transponder key sends out a unique signal to your automobile’s computer, a singular frequency aligned only to your vehicle. When the signal is received, the mechanical part of the key releases the steering lock, so you can activate the ignition to start up your car.

Did you lose your transponder key?

Misplacing your car key is much more problematic than it used to be decades ago. With a basic key, you could have a duplicate made for almost nothing, at any local locksmith or hardware store or, or even at the dealership. But a transponder key is a different story. When you know it’s time to give up on trying to track down your transponder key, replacing it will surely cost you. Depending on the intricacy of the key’s design, as well as on the automaker, the replacement of your electronic fob will be expensive to some extent, or perhaps enormously so. Some dealerships will reprogram your key fob at no charge, but most will charge you a whole lot.

For some vehicles, a transponder key is an all-in-one unit, with a fob. Also referred to as a laser-cut key, the shank is a bit thicker, with fewer carved-out grooves. Laser-cut keys are sometimes called “sidewinder” keys, because of the winding cut feature on the shank. The dealership will likely have to program a laser-cut key’s built-in chip.

A smart key isn’t really a key; it’s just a fob. You either insert it into your dashboard, or, you can keep it in your purse or pocket. When you’re behind the wheel, you can start or stop the car simply by pushing a button. A smart key gives you better security because of its rolling security codes. Continuously randomizing the right code, it prevents a car thief from hacking it with a code grabber. Your car dealership will certainly be able to replace your smart key.

A switchblade key is another sort of transponder key that has a shank, but it folds into the fob, and you can pop it out by pressing a button. A switchblade key has either a basic cut or a laser cut. One benefit is that you can purchase the components separately. If you've definitely lost your key, you need to get both parts programmed.

Is your transponder key not working?

  • One common reason that your transponder is malfunctioning is that there’s a manufacturer’s defect. If your vehicle is under warranty, then you’ll be able to correct the problem at the car dealership for free. If it’s not under warranty, then it’s time to hire an automotive locksmith.
  • There might be a foreign object stuck in the ignition. Don’t attempt to extract it yourself, because you could easily damage the ignition. Hire an experienced professional automotive locksmith instead, someone who can remove anything from the ignition mechanism with the exacting precision required, so won’t have to replace the whole switch.
  • Another possibility is that your transponder key isn’t properly communicating with your automobile’s computer, because the chip has lost its programming. You can get it reprogrammed, or, you can get a new transponder key with new programming. Whatever you decide, an automotive locksmith or your car dealership will be able to handle it.

What if your transponder key was stolen?

When you first bought your vehicle, you should have gotten two transponder keys with it. It’s probable, then, that a family member has your additional copy, which for now will get you going. But bear in mind that, because your transponder key is connected to your car only, a potential car thief who finds your key can easily take your vehicle. That means you’ll need to get a replacement transponder key, and then reprogram them both.

To get a transponder key made, reprogrammed, or replaced, find an automotive locksmith specialist, or head out to the dealership. A locksmith company will generally cost less than your dealership. If you’re anywhere in Racine, Wisconsin, bring all your questions to a reputable automotive locksmith mobile specialist, such as a locksmith professional on staff at Racine Locksmith, where free consultations are available.


If you have to get your transponder key reprogrammed, with some vehicles, you can program the transponder key yourself.

The following will be a successful method on a lot of American-made cars, so you may be in luck. However, before you should spend any money, check your owner's manual, ask your dealership, and/or inquire at a local automotive locksmith technician to see if this procedure will work on your car:

1. First, insert one of your two functioning keys. Then, turn the ignition to the "on" position for about 3 seconds (don’t start the car).

2. Do the same thing with the second key.

3. Now, insert the new third key, and turn it to the "on" position, again for about 3 seconds. This will program your extra key properly.

If you often lock your keys in the car, you can still get inside your vehicle. Order only the standard key, but not the transmitter. Then you’ll at least have a key that does everything except start up your car.