URGENT ECU changed - recover transponder code

[carNoob1]

Hi,

I recently purchased my first car, a 2007 Citroen C2 1.1L which has apparently had it's ECU changed. I have have had a spare key cut (as i only had the one key) but when the guy came to program it, the code i had on the plastic card in the owners manual did not work so i am assuming its for the old ecu.

Is there anyway i can find out what the correct code is so the key can be programmed ?

If it cannot be recovered, how difficult is it to replace the ECU as i have seen a few on eBay that come with a keycode ?

Any help would be much appreciated.

[GiveMeABreak]

Speak to a Citroen main dealer - as you don't have the code for the current set they may have to send off the working key to obtain the code - that's not something they can usually do in the dealers. I'm not sure if they can extract the code from the ECU directly. They'll be able to confirm.

[xantia_v6]

Speak to a Citroen main dealer - as you don't have the code for the current set they may have to send off the working key to obtain the code - that's not something they can usually do in the dealers. I'm not sure if they can extract the code from the ECU directly. They'll be able to confirm.

You can't recover the code from a key, the key transponder chip is coded at the factory long before it is associated with a car, it is the car that is coded to the key.

I think you need a new ECU, or have your current ECU re-virginated.

[GiveMeABreak]

It's odd that they took our second plip and sent it off when we needed another one made, they then gave this back with the new one when it arrived a week or so later.

[RichardW]

You can't recover the code from a key, the key transponder chip is coded at the factory long before it is associated with a car, it is the car that is coded to the key.

I understood it's the other way round..... the chip is blank when it comes, and the car writes the code to it when you program it - and this is a one shot operation hence you can't program a 2nd hand key to another car (unless you change the chip for a blank one).

If you see the recent thread, the ECU and BSI have to match the code - and you only get one go at writing the code to the virgin BSI, and if you get it wrong it's U/S and needs to be virginised. If the ECU has been changed on the car then the BSI has also been changed (and virginised and re-coded) - and hence the code you've got is wrong. It may well be possible to extract the code from the BSI using the appropriate kit - I've seen a youtube vid of this. Not entirely clear from the original post - but it appears to have a working key, and the requirement is just to get a spare.

[xantia_v6]

I understood it's the other way round.....

You are correct and I was mistaken on this one.

[GiveMeABreak]

Is there anyway i can find out what the correct code is so the key can be programmed ?

So as Richard says, if you have had the BSI and ECU replaced already with a working key already programmed, then Citroen should be able to find the new code from the car using their kit (for a fee). From this you should then be able to get a new one coded.

[RichardW]

Lexia / Daigbox won't do it - you need a specialist aftermarket bit of kit, eg see this from about 1:40 in: