If your car was built in roughly the last twenty-plus years, there is a good chance its key has a small electronic chip inside the plastic head. That chip, called a transponder, is a big reason car theft by hot-wiring became so much harder. It is also why replacing a car key is not as simple as cutting a piece of metal.

How it works

When you turn the key or press the start button, the car sends a short radio signal to the chip. The chip answers with a code. If the car's immobilizer recognizes that code, it allows the engine to run. If not, the engine may crank and stall, or not crank at all.

Signs your key has a transponder

• A thick plastic head on the key, rather than all-metal.
• A remote or buttons built into the key.
• A push-button start system.
• An immobilizer or anti-theft light on the dashboard.

Common transponder key problems

The car will not start with a copied key. The blade was cut but no chip was programmed. The key turns, but the immobilizer blocks the start.

The security light flashes. The car is not reading the chip. The chip may be damaged, or the key may have lost its programming.

A dropped or water-damaged key stops working. The chip is small and can crack or fail.

Getting a replacement or spare

A working spare needs the blade cut to your locks and a chip programmed to your vehicle. Have the year, make, model and VIN ready, along with proof of ownership. Getting a spare while you still have one working key is usually simpler than replacing the last one.

Choice City Locksmith provides transponder key service in Fort Collins, cutting and programming keys at your vehicle. Phone (970) 803-1100.