In short
A modern car key has three parts: the blade or mechanical part, the transponder (a chip the immobiliser has to recognise before it lets the engine start) and the remote fob that locks and unlocks the car. Making a new key is, above all, registering the transponder in the car's immobiliser. If you have a key that works, we start from it; if you've lost them all, the immobiliser data has to be accessed from the vehicle's control units. The price is on request, depending on the model and the type of key. We do it at our workshop in Alcalá de Henares or as a mobile service within the Community of Madrid.
How a key with an immobiliser works
For many years now, turning the key or pressing the start button hasn't been enough to start the engine. The car first asks the key who it is:
The three parts of a key
- Blade or mechanical part
- Opens the door by hand and, on cars with an ignition barrel, turns the ignition
- Transponder
- A battery-free chip that the immobiliser reads by radio and has to recognise as its own
- Remote fob
- A battery-powered transmitter that locks and unlocks; it is independent of starting
The immobiliser stores the list of authorised transponders. It may be in its own unit, in the engine ECU, in the comfort module or spread across several of them. A new key only works once its transponder is on that list. That's why "copying" a key isn't just making an identical one: it's teaching the car that it exists.
I have one key and want another
This is the simplest situation. With a working key, the immobiliser can be accessed through the diagnostic port or by reading the unit where it's stored, and the new one added. The process, broadly speaking:
- We check what type of transponder and remote your key has.
- We prepare the new key with the correct transponder and frequency.
- We register it in the immobiliser alongside the one you already have, and synchronise the remote.
- We test both: starting, unlocking and locking.
Tip: if you only have one key left, don't wait until you lose it. Having a second one costs much less than solving an all-keys-lost case.
I've lost all my keys
Here there's no key to start from, so the immobiliser data has to be reached another way. Depending on the car, that means reading the memory of the module that stores it (sometimes by removing it) so that new keys can be registered. It's a longer and more delicate job.
What you need to know:
- The car can't be moved under its own power, so we normally come to you. We explain it in mobile service.
- Take the opportunity to make two keys: that way you won't end up in this situation again.
- The lost keys are left out: when the new ones are registered, the old ones stop starting the car.
If the immobiliser module is also faulty, the job is combined with BSI cloning or engine ECU cloning, depending on where the data is stored.
The key exists, but it won't start the car or unlock it
Before making a new key, it's worth knowing whether the one you have can be saved:
| Symptom | Likely cause | What we do |
|---|---|---|
| Won't unlock remotely, but starts | Flat remote battery or remote out of sync | Battery replacement and, if needed, synchronisation |
| Unlocks, but won't start and the immobiliser warning light comes on | Damaged transponder or one that has come loose inside the casing | Transponder check; if it fails, a new key |
| No key will start the car | Immobiliser aerial, immobiliser module or engine ECU | No-start solutions and diagnostics |
| Works on and off | Broken casing, worn buttons, contacts | Casing replacement keeping the electronics |
| Keyless key isn't detected | Low battery or interference | Try with the key in the emergency position shown in the handbook |
If all the keys fail at once, it would be odd for them all to have broken on the same day: the problem is almost always in the car, not the keys.
Keyless keys
On cars that unlock and start with the key in your pocket, the key communicates with several aerials spread around the car. That brings two particular points:
- Programming is usually more demanding and, on some makes, depends on modules with extra protections. With the make, model and year we'll tell you whether we can do it.
- When the battery runs out, the car almost always has an emergency spot (on the steering column, in the cup holder or under a cover) where you hold the key to start it. Check the handbook before giving the key up for lost.
What we'll ask you for
To give you a price and a timescale we need:
- Make, model and year of the car, and whether it starts with a turning key or a button.
- How many keys you have and whether any of them work.
- A photo of the key (if you have one), both sides.
- Where the car is, in case we need to come to you.
To make a key we'll ask for the vehicle's registration certificate (permiso de circulación) and the registered keeper's ID (DNI), or an authorisation from the registered keeper if that isn't you. It's how we make sure the key is for someone who is entitled to it.
The metal blade is not cut at our workshop: we take care of the transponder, the remote fob and the programming in the immobiliser.
How much it costs
Key copying and programming is price on request. The price depends on:
- The situation: adding a key when you have another is the simplest; all keys lost, the most laborious.
- The type of key: with blade and remote, flip key or keyless.
- Where the immobiliser is in your car and how it has to be accessed.
- Whether we come out to the car.
We give you a fixed price before we start. You can ask for it using the quote form.
Tell us what's happened (you want another key, you've lost them or it won't start) and, if you have one, send us a photo of the key. We'll tell you how we'll sort it out.
Reviewed on .