C4 '06 - Programming new remotes & keys

[teuski]

Hi!

I just bought a '06 1.6 16V C4 for my wife. The car has only one working key, and that is without remote. I also got spare parts donor in the same bundle

What should i do now to get a (preferably extra) fully working key with remote? Is it possible to reprogam a pre-used immo chip and/or remote from the spare parts donor to the other car?

I have:

• working normal key for the car
• a chinese remote fitted with a working blade but no immo
• almost new looking official remote key for the spare parts car
• no confidential code card
• Lexia

The seller said he bought the chinese remote to replace the broken original one. He was absolutely sure that the immo chip was on th PCB of the remote (really?) and he broke it while trying to pry it off ( ). Anyways he ditched the broken remote but for the blade, which he fitted to the said chinese remote fob. And of course he never got the remote working...

[Paul-R]

Have you got a pic of the bits you've got that you can post?

How much of the original blade did he save? If it was just literally the metal blade then he probably ditched the chip. If your fob is the same or very similar to the ones I had for my 2001 Xsara and 2003 C5 then the chip is in the little bit of plastic that the blade is embedded into. The chip was definitely not on the circuit board - that is only for the operation of the buttons (lock/unlock and possibly a third option).

Just as an experiment try putting your working key into the ignition and then press any of the buttons on the Chinese remote. Keeping the button on the Chinese fob pressed turn the working key to the ignition position and leave it there for 5 - 10 seconds. Take the working key out, get out of the car, close the doors and then try to lock the car using the Chinese remote. It might just work that way.

[Hell Razor5543]

Typically keys are made up of three discrete parts. The obvious one is the blade. Then there is a small capsule, typically glass, which contains the circuitry to handle the immobiliser system. Finally there is the remote locking circuitry. All three parts are contained within the fob.

If the C4 system is anything like that of the C5 the immobiliser key chip can only be programmed once, and then it 'locks' to the car. You may well have to buy a new keyfob, get the blade cut, and then 'introduce' the new key (and ALL other working keys) to the car (any working key that is not 'introduced' to the car will be forgotten). You will need the four digit confidential code (you can get this from Citroen upon proof of ownership of the car. They may charge a fee) to 'prove' to the ECUs that you are allowed to do this. As I have not had to do this I cannot explain how to 'introduce' the keys to the car.

If you have the owner handbook it should explain somewhere how to re-introduce the remote locking system to the car (try looking for 'replacing battery in fob'). Typically you turn the key in the ignition to a position in the ignition (M, I believe), and then press and hold one of the remote keys for a while (lock might be best). After a few moments the car should lock. This would mean the remote has paired with the car, and the remote locking should now work properly.

[411514]

I'm fairly sure that on your remote the immobiliser chip (which is a conductive coil set in a small resin block) is not mounted to the central locking PCB. On my partner's 55 reg. C4 the immobiliser chip is fitted in a little slot formed in the key housing. Might be worth checking the broken housing (if you still have it) to see if the chip is still there.

I should imagine that the same immobiliser chip is housed somewhere in the non-remote key. Thus, you might try taking the immobiliser chip from the non-remote key and fitting it to a new remote key housing with the blade cut. Making the central locking work is then relatively easy.

[teuski]

The remote is not like the rounded one on C5 I and Xsara but a square one like in newer Citroens. I am familiar with the older key, but at a glance in this newer one the blade part is just solid metal.

The non-remote key can be pried open and it contains a black chip bit similar to older keys. I haven't taken a closer look at a remote key yet. I only opened the chinese one and it seems to have a slot for a traditional chip.

I also know the Lexia key pairing procedure and that i can get the code from a citroen garage. But will my chips and remotes work with that as they are already programmed to an another car? Or do i have to get a blank chip?

As for the chinese remote i have to try the just-the-key pairing procedure but keep in mind that remote was never actually programmed for the car in question.

I can start the car with that key if i hold the key with the immo chip next to the immo antenna at the ignition lock.

[GiveMeABreak]

On the C4 (2006) this is the internals of the remote fob and the transponder chip is shown as the cylindrical object at 'a'

As the BSI, Engine ECU and Transponder are all based on the confidential code they need to be the same set. 'There is an encrypting function is known by the BSI and the ignition key transponder. This function permits encryption of the transponder password and decryption of the result sent by the ignition key transponder by the BSI'.

[411514]

'There is an encrypting function is known by the BSI and the ignition key transponder. This function permits encryption of the transponder password and decryption of the result sent by the ignition key transponder by the BSI'.

I have heard this before somewhere but do not appreciate how it could correct. The immobiliser chip is entirely passive, it is simply a conductive coil energised to emit RF radiation by the ignition barrel mounted reader. As far as I am aware there is no way in which the response of the immobiliser chip to the applied field could be varied - either its response is the correct RF frequency or it isn't.

[GiveMeABreak]

The identification procedure consists of interrogating the ignition key transponder via the transponder coil in order to obtain the ignition key transponder identifier.

This is the functional description:

• The BSI sends an identification request to the switching module under the steering wheel
• The switching module under the steering wheel generates an electric signal for the transponder coil
• The transponder coil transmits the message to the ignition key transponder in the form of a high frequency signal (125 KHz)
• The ignition key transponder replies by sending its own transponder identifier
• The key transponder identifier is compared with the key identifiers stored in the BSI
• If the key transponder identifier is stored in the BSI. The key transponder authentication procedure can begin
  If the key transponder identifier is not stored in the BSI. The procedure is repeated every 100 ms for 2 minutes

[teuski]

It would be nice to have a spare key, for which i need to get the immo working. But the biggest question at hand is how can i get remote locking to work? I have tried the pairing procedure (ignition on with the immo-ok key, press 10sec lock etc.) for both the remotes with no success. I guess i should try it out with new batteries.

Does the lexia pairing do something to the remotes too or not? Should it even be possible to just pair an another car's remote with the aforementioned procedure?

Here are pictures of the internals of the keys. The right remote is the chinese one with the correct blade, the one on the left is a delphi one from the parts car.
On the non-remote key the immo chip is clearly visible.

The delphi remote has the coil as in GiveMeABreak's pic, the chinese one has empty clamps in the place of the chip. Looks like there might have been a coil, but the someone might have taken it off. But on the housing there is a slot at the same place that looks like it could hold the old style black immo chip.

[GiveMeABreak]

As far as I can see you will need the original transponder chip from the original keys to be able start the car. The BSI can store up to 5 keys and their IDs. I doubt you can use another transponder chip from another car’s key.

When pairing you need to pair the total number of keys you will be using on one Lexia programming session.

[xantia_v6]

Do your 'remote' keys have immobiliser chips on the other side of the PCB?

[Hell Razor5543]

The circuit boards are for the remote locking function. It would certainly be worth fitting them with new batteries. If you look at the plain key you will see a small black object, close to and below the blade. This is the immobiliser chip. On the circuit board to the left there is something that MAY also be an immobiliser chip (although the circuit board to the right does not have this chip). The left casing has the position for that chip on the board, while the right casing has a space for a separate chip. I wonder if it is possible to buy a separate chip, and then fit it into that position. I do NOT know if the C4 chip has to be unused before it is introduced to a car, but I know that the C5 chip does (I believe that Ben82 tried to pair a used key with his C5, and was unsuccessful).

https://www.frenchcarforum.co.uk/forum/ ... =3&t=42964

[GiveMeABreak]

Do your 'remote' keys have immobiliser chips on the other side of the PCB?

Not on the C4 (2006) fobs. They are as illustrated in the picture I posted previously of the fob.

[xantia_v6]

The diagram that you posted appears to show the immobiliser chip on the same side of the PCB as the battery, which is not visible in the photo posted by teuski.

[Paul-R]

On the circuit board to the left there is something that MAY also be an immobiliser chip (although the circuit board to the right does not have this chip). The left casing has the position for that chip on the board, while the right casing has a space for a separate chip.

I've looked at both the circuit boards carefully and I can't see anything in one that isn't in the other, although the black chip and tin can (resonator?)at the top right are different types.

I then prised my X7 remote fob open and AFAICS it's exactly the same as the board on the left. The item (a) on Marc's drawing isn't a chip it's a coil. Unless the immobiliser chip is inside the coil (unlikely I would think) that's not where it is.

I really need a complete key fob off a scrapper that I can really take to pieces so I can become as familiar with things as I was with the ones off the Mk 1 C5 and Xsara.