re program C5 fob

[Ben82]

deano, I've looked at gallalock before, I believe they are one of the "auto locksmiths" that I was talking about, so the keys should be virgin keys. I've not used them so have no idea how legit they are.
eBay has plenty of people selling second hand keys, probably not even aware that they cannot be reprogrammed to another car, and they find the re-pairing instructions and think that would work to the person they sell them to. And of course people probably trying to make a quick buck out of other people not really investigating whether they can program a key to a different car.

I have however recently contacted these guys, who were very informative, stating that they can only get information for UK registered vehicles to be able to verify ownership, and suggested I either go to a Swedish auto-locksmith, or failing that the dealers. Their header also says about a 24hr telephone number, so you could give them a call and discuss your issue, they also have the bit on that page about the warning about buying 2nd hand keys from eBay/Scrappies.

[deano1970]

ok, cheers everyone for the info. I will ring gallalock on monday and ask them about the fobs,and yesmI was intending to get the blank key cut to my car, but only as long as the fob also unlocks/locks my car.I will let you know how i get on...........thanks again......

[kentc5]

Hello guys,

As far as I understand and I researched before, there is no info stored on the fob it self about the car. Even if the fob is used from another car, it can be paired to another car, as long as someone with Lexia pair it with the car.
The fobs do not come car specific. The blades on the fob do.

I have a used fob where I removed the blade and I am putting in a blade from my car inorder for that to work.
Now the only thing left is to pair the key with the car but need for the weather to get better.

Mind you this is the case with some cars that the fob once it is programmed at a car it cannot be reprogrammed but not with the C5(1) as far as I know.

No need to ask locksmiths because they all told me that it cannot be reprogrammed they will not be even try as they want to sell me their keys! They will not even bother if it is not their product.

[Hell Razor5543]

As far as I am aware, part of the elctronics in the fob ARE specific to the car. This is the immobiliser circuit, and this is read by the inducer circuit in the ignition barrel. Once this has become programmed to the car it cannot (with some chips) be erased and re-used. The locking part of the fob is battery powered, and needs to be re-introduced to the car when the battery is changed.

On my previous Xantia one key didn't start the car (and I got the immobiliser light on the dashboard). A colleague with a very steady hand re-did all the solder joins (and they were on surface mounted parts), and then the key would start the car.

It appears that C5s need the battery in the fob to help drive the immobiliser circuit;

http://www.frenchcarforum.co.uk/forum/v ... ob+battery" onclick="window.open(this.href);return false;

[Mandrake]

I think we're getting well into the territory of hearsay and conjecture in this thread now hell razor

The need of the battery in the fob to operate the immobilizer on early C5's was debunked in that very same thread you linked... The battery is only needed for the remote RF transmitter to work, the immobilizer chip is passive very much like an RFID card - it gets its power by induction.

Also both the RF transmitter code and the immobilizer code on the chip on the key are permanently fixed - the pairing process teaches the computer on the car the codes in the key, nothing on the key is changed by the pairing process.

On a Xantia as long as you have the 4 character security code for the car you can pair any RF transmitter and immobilizer transponder (new or second hand) by using a Lexia. (Obviously the actual key blade would need to be swapped over or cut to match) I know because I've tried it on my Xantia.

What we really need is someone with a similar model of C5 and a Lexia that can have a look at the programming options in the Lexia to see whether it can be done or not. My guess is that it can be.

deano: what year and model is your C5 ? I'll have a look in the Citroen service data to see if I can find any information on key programming for the C5.

[Peter.N.]

My head aches

[Mandrake]

While we're waiting for deano to confirm the year of his C5, I've attached a copy of the programming process for the original C5. It's a zipped PDF file.

As far as I can see the programming process looks identical to to a Series 2 Xantia - eg both the transponder and RF transmitter are coded to the BSI (CPH in a Xantia) using a Lexia. It also says that when you add an additional key that all existing keys must be reprogrammed too - same as a S2 Xantia, any existing keys that are not reprogrammed are "forgotten".

My interpretation of the document is it should be possible to program a second hand key/fob with the Lexia. I would avoid mixing keys between different versions of the C5 though - C5, C5 facelift, C5 X7, as there may be differences between them.

[Peter.N.]

Thanks for that, I have printed it out, I need to do the red C5 - if I can get my Lexia to work again

Peter

[deano1970]

hi mandrake, sorry, been to work today.... it's an 03 2.0 hdi sx 110..........not over bothered about even having the key working as long as i can lock/unlock the car while cold weather stops me doing it with the only key I have.....as I said, http://www.gallalock.com" onclick="window.open(this.href);return false; are selling new C5 fobs for my car and year for £67.00 with an ucnut blade, seems reasonable as long as it can be programmed to lock/unlock my car?? my head also aches...........that's cos i'm stupid though..

[deano1970]

oh and thanks for the file regarding adding keys. I don't have a lexia but am thinking of buying one........so, looking at that it would seem a new fob can be programmed to a car? That has to be the case as the site that sells them as new would be selling worthless fobs?? thanks everyone for their input

[kentc5]

or if you have a lexia buy a used one for £8 as I did ... and experiment nothing much to loose if it works you are a winner lol
if it does not you loose less money

[deano1970]

the question is kentc5 is, did it work for you?? you didn't tell me that bit?? cheers....

[kentc5]

I started going through with the list of people with Lexia's around my area. Contacted a couple and one came back to me, and his laptop was broken.
My work has picked up so waiting for free time to continue through the list.

The biggest problem is even if you get a brand new fob who will program it for you? as any auto locksmith I tried to call here in Kent they will not touch something they have not supplied. It is like they are all agreed on it between them.
So be careful before you buy one.

But I have read on threads on here before that people have managed to pair a used remote on a C5 from another C5. That was when I was looking 2-3 months ago as my car came only with one fob and I wanted just the safety in mind of having a spare.
But I do have the Citroen scratch key code which is essential to program a key in. Without that from what I understand it is not possible, hence you have to go to Citroen to obtain the code. That code enable the Lexia to unlock extra pairing settings? this is what I believe happens... but someone correct me

[kentc5]

Here is my post ... if you see JohnD has done it with a used remote
It can unlock and start the car but it will not lock, I think it might be a problematic used fob rather than anything else.
http://www.frenchcarforum.co.uk/forum/v ... =3&t=41873" onclick="window.open(this.href);return false;

[Mandrake]

But I do have the Citroen scratch key code which is essential to program a key in. Without that from what I understand it is not possible, hence you have to go to Citroen to obtain the code. That code enable the Lexia to unlock extra pairing settings? this is what I believe happens... but someone correct me

Yes the scratch key code (4 characters) is essential to do any pairing of keys/fobs with the car, also to change any security/alarm related settings on the car such as permanently disabling the alarm etc.

You don't need to go to Citroen to get the code if it's lost though, I got mine from "The Birdman" for a small fee along with the radio code. (The scratch card was long gone when I bought my Xantia and I wanted the radio working... )

From looking at that thread I would say one of the buttons was faulty on John's fob - I had the same problem with my Xantia fob at first - it would unlock but not lock. Opened it up and found the lock button floating around loose inside the case! Re-soldered both buttons and it works fine now. If a fob can unlock the car the pairing was successful, being able to unlock but not lock just means the fob has a fault...maybe fixable with a bit of soldering, maybe not.