Quick answer: a transponder key has a small chip in its head that the car’s immobiliser checks every time you start it. If the chip is missing, damaged or not programmed to that car, the engine won’t run even though the key turns. Replacements have to be cut and programmed to your car, which we do at the car for Japanese, Korean and most American makes.
Nearly every car sold in Australia since the early 2000s has a transponder key, and most people only find out when a hardware-store copy turns the ignition but won’t start the engine. Here’s what’s going on.
What the chip does
Inside the plastic head of the key is a tiny glass or ceramic chip with no battery. When you turn the key, or press start with the key in range, the car’s immobiliser sends out a signal, the chip answers with a code, and if the code matches one the car knows, the engine is allowed to run. No match, no start. It’s why car theft by hot-wiring disappeared.
Why a copied key doesn’t start the car
A key-cutting kiosk can copy the metal blade, so the copy opens the door and turns the ignition. But the car has never been told about the new chip, so it refuses to start. That’s not a faulty key; it’s the immobiliser doing its job. The new key has to be programmed to the car with the right equipment.
What goes wrong with transponder keys
The chip cracks. Keys get dropped, sat on and put through the wash. A cracked chip means the key turns but the car won’t start.
The key loses its programming. Rare, but it happens after a flat battery, a jump start or work on the car’s electrics.
The blade wears. After years of use the cuts round off and the key starts sticking. The chip is fine; the blade needs recutting.
You lose the only one. With nothing to copy from, the lock has to be read and the car programmed from scratch. See lost all your car keys.
Which cars we program keys for
All Japanese cars (Toyota, Mazda, Honda, Nissan, Mitsubishi, Subaru, Suzuki and others), Hyundai and Kia, and most American cars including Ford and Holden. We come to the car and do the cutting and programming there; most keys are done in about half an hour once we’re with the car. European and Chinese cars use systems we don’t program, so their keys go through the dealer, though we can still open them if you’re locked out. The full list is on car makes we cover.
Transponder key, remote key or smart key?
A plain transponder key has the chip and nothing else. A remote key adds buttons to lock and unlock, which are paired separately from the chip. A smart or proximity key stays in your pocket and talks to the car by radio; it still contains a transponder as a backup. We supply and program all three. See remotes and smart keys.
Common questions
Can I get a transponder key copied at a hardware store?
They can copy the blade, and some kiosks can clone a chip for older cars, but for most cars since about 2010 the key has to be programmed to the vehicle. We do that at the car.
How do I know if my key has a transponder?
If your car is newer than about 2001 and the key has a thick plastic head, it almost certainly does. A quick check: if a plain metal copy turns the ignition but won’t start the engine, that’s the transponder.
Can you make a key with just the VIN?
Not on its own. We read the lock at the car to get the cut, then program the chip to the car. The car has to be there.
Does a transponder key need a battery?
The chip doesn’t. The remote buttons on a remote key do, which is why the doors can stop responding while the engine still starts.
Need a transponder key programmed?
Call 0427 580 823Send an enquiry
Service page: transponder keys. Near our base: Kingsley.