Transponder chips: a working reference
What each transponder chip family is, which can be cloned and which must be programmed, and how to identify the chip in a key you are holding.
The transponder decides how a key job goes: whether you can clone in two minutes or have to connect to the car, and whether a lost key is a spare or a full immobiliser procedure. This is a reference for the families you meet most.
How to identify the chip you have
Three routes, in order of reliability. The chip type is sometimes printed on the key or on the transponder glass itself. Failing that, a transponder reader identifies it in seconds and is the tool worth owning if you do this daily. Failing both, the OEM part number on the fob board narrows it to a family.
Guessing from the vehicle badge is the one route that fails, because a single model year can carry more than one chip depending on where it was built and what was fitted.
The fixed code families
These carry a code that does not change, which is what makes them copyable onto a blank without ever connecting to the vehicle.
- 4C: an early fixed code transponder. Straightforward to clone with almost any cloning device.
- 4D: a large family covering a great many vehicles. Cloneable in most cases, and the workhorse of the cloning trade.
- ID46: a crypto transponder that can usually be cloned onto a suitable blank, though it takes longer than a 4D because the tool has to calculate rather than copy.
The rolling code families
These change their response each time they are challenged, so there is nothing static to copy. A new key has to be written into the immobiliser.
- ID47: widely used and, in general, programming only.
- ID49: a later generation, programming only.
- 8A: common on more recent vehicles, programming only.
What this changes about the job
If the chip clones, you need a cloning device, a blank that accepts the chip family, and a way to cut the blade. The car is never touched. If the chip does not clone, you need a programmer that supports the platform, access to the vehicle, and possibly a security PIN read first.
That is the difference between a bench job and a call-out, so it is worth establishing on the phone.
Blanks and shells
A blank has to accept both the chip and the keyway. Getting one right and the other wrong is the most common ordering mistake in this category, and it is why every blank listed here states the keyway code, and states the chip where the chip is fitted rather than empty.
Questions
Can I put any chip in any blank?
No. The blank has to physically accept the transponder and the blade profile has to match the lock. Both are stated on each product page where we hold them confirmed.
Is a cloned key as good as a programmed one?
For the vehicle, yes: it behaves as the original does. The limitation is that some systems count authorised keys, and a clone does not add to that count, which occasionally matters later.
How do I read a chip with no working key?
You cannot read what is not there. All keys lost is an immobiliser procedure rather than a chip identification problem, and the route depends on the platform.
About this guide
This is general information about how the work is normally done, not advice for the particular vehicle, lock or machine in front of you. It does not replace manufacturer instructions, training, or your own judgement about whether a job is within your competence. Specifications and fitment change between model years, so check the code on the original part before you buy or cut anything. See the terms.