What is a transponder key, and does my car have one?
A transponder is a tiny chip inside the plastic head of your key. It has no battery. When you turn the key, an antenna ring around the ignition sends out a weak signal, and the chip answers with a code. If the car's immobilizer recognizes the code, the engine is allowed to run. If it doesn't, the car won't start, even with a perfectly cut key.
Canada made immobilizers mandatory on new cars in 2007, and many makers, including Ford, GM, Toyota and Honda, used chip keys years before that. If your key has a thick plastic head and your car is from the 2000s or later, assume there's a chip in it.
What's the difference between the chip, the remote buttons and a smart key?
People mix these up all the time, and it matters, because each one is a separate system. A key can have a perfectly good chip and dead buttons, or the other way around.
| Part | What it does | Battery? | When it fails |
|---|---|---|---|
| Transponder chip | Tells the immobilizer this key is allowed to start the car | No | Car cranks then dies, or won't crank. A key or padlock light may flash on the dash. |
| Remote buttons | Lock, unlock, trunk and panic from a distance | Yes, a coin cell | Buttons stop working, but the key still starts the car |
| Proximity smart key | Opens the doors and allows push-to-start while the fob stays in your pocket | Yes | "Key not detected" warnings. See our smart key page. |
If the buttons stopped working but the car still starts, you probably don't need programming at all. Put a fresh battery in the remote first.
Need transponder key programming now? A real person answers 24/7.
Call (647) 367-8113Why does my car crank but not start with a new key?
That's the classic sign of a chip problem. The blade is cut right, so the key turns, but the immobilizer doesn't know the chip. The usual reasons:
- The key was cut at a hardware store or mall kiosk, but the chip was never programmed or cloned
- It's the wrong chip type for your car, which is common with cheap keys bought online
- The chip cracked when the key was dropped, or fell out of a broken head
- Less often, the car has a fault in the antenna ring or the immobilizer itself (more on that below)
Watch the dash when you turn the key. A flashing key or car-with-padlock symbol usually means the immobilizer isn't reading the chip.
How does car key programming work?
There are two ways to do it, and your car decides which one we use.
- Cloning copies the code from your working key onto a new chip. Nothing gets plugged into the car. It works for many older chip types and is a fast way to get a spare.
- On-board programming means connecting our programming tool to the diagnostic port under the dash and adding the new key to the car's list of approved keys. Most newer cars need this, and it's the only way when every key is lost.
Remote buttons are programmed as a separate step, sometimes with the same tool and sometimes with a sequence done in the car. On some models, adding a key also deletes every key the car doesn't see during programming. That's useful when a key was stolen, and it's why you should have every key you want to keep with you.
If you've lost the key entirely, start with car key replacement, since the blade has to be cut before the chip can be programmed.
Can a locksmith do car immobilizer repairs?
Partly, and here's the honest split. When the problem is the key, a locksmith is usually the fastest fix. When the problem is inside the car's electronics, you need an auto electrician or the dealer.
| Problem | Who fixes it |
|---|---|
| Key not programmed, wrong chip or damaged chip | Locksmith: reprogram or make a new key |
| Lost or stolen key that still starts the car | Locksmith: erase it on most models |
| Worn ignition that no longer reads the key well | Sometimes a locksmith. Ask when you call. |
| Failed immobilizer module, engine computer or wiring | Auto electrician or dealer |
| No-start that began after a remote starter install | The installer first. Remote starters often use a bypass module that can cause this. |
| Dealer-locked systems on some European luxury cars | Dealer |
We don't bypass or switch off immobilizers. If someone offers to, say no. It leaves your car much easier to steal.
What happens when you call?
Tell us what the key does
Turns but won't start, starts some days, or you just need a spare. Plus the year, make and model.
Check it can be done
Dispatch confirms your chip type is supported and gives you the price. Dealer-only cars are flagged right away.
Clone or program at the car
We check ownership, then clone your working key or connect to the diagnostic port and add the new key.
Test every key
We start the car with each key you want working, and erase any lost ones if you asked.
Page reviewed October 2026 by the LocksmithGT team.