Xantia V6 CPH/engine ECU swap and transponder programming

[Mandrake]

Hi All,

Looking for a bit of advice here.

I'm investigating the feasibility of a temporary engine ECU swap on my S2 Xantia V6, to try to rule out the ECU as the source of my ongoing intermittent engine running/performance/misfiring issues...

I'm aware that the ECU is paired with the CPH, however I may have access to a pair of ECU's from a donor car that I can borrow for testing.

So my questions are:

1) How hard is it to swap the CPH over ? I know addo has said he can swap one by removing the glovebox, but how exactly is this done and how much work is it ?

2) Can already paired transponder chips in a S2 Xantia be reprogrammed to work with another CPH ? (And then back again later ?) I know they can't be reused on a C5, but can they on a Xantia ? Does anyone know for certain ?

What I would like to do is swap the donor CPH and engine ECU into my car, and use the Lexia to program the donor CPH to recognise my existing RF remote and transponder chips. Is this possible ? Or is it necessary to physically swap the transponder chips in the keys over ?

Any advice gratefully received.

[addo]

This is a fifteen minute job, done with ignition off. You need a 10mm nutdriver or spanner, and a T20 screwdriver.

1. Lift the bonnet and take the ECU box top off. Lift out the guts. Unclip the ECU plug, and unbolt the ECU from the slide-in plate (10mm heads) - replace ECU and reassemble box/lid. Disconnect the battery.

2. Open glovebox. Remove screws in rubber buffers at top. Remove screw on right side near check strap. Peel up felt and remove screws on left lower side and across the base. Ease the glovebox forward - when all screws are out it will come free readily. Look for the orange airbag wire clipped to the side of the glovebox shell and prise the clip loose. Pull the box out a little further and disconnect the white plug at its rear base. You can now set it aside.

3. Remove the T20 screw now exposed at the upper right of the opening, it holds a white nylon bracket heat welded to the air duct. Push the ducting hard left to free it from the HVAC box and bring the right side forward, then it will come free at the left side locating peg, in your hand. Now look to and see the yellow and black plugs at the front of the CPH.

4. Pull the red tag on the black plug, to the left to release it - it's like the Bitron or cruise control plugs. On the right plug (yellow) you need to gently depress the lock tab in order to slide the locking bar (a black strap) towards the left; the action of hingeing it works like the ECU plug. The CPH is now disconnected.

5. Identify the little ramps on the front edge of the CPH's black plastic mounting tray. With your right fingertips, pull the tray's front lip down whilst using your left hand over the top of the box to push it forwards. Be confident and it will come readily. Slide in the other CPH, reconnect the plugs and (optional) refit the glovebox. I write the immobiliser code and donor VIN on both ECU and CPH with marker pen.

6. Remove the two screws on the steering column cowl that secure the top half - take this off. Now pull the lower cowl half downwards at the front to clear the wheel, then towards you and to the left to clear the rear locating tab (check for a third screw!) and angle adjustment lever. As the cowl bottom comes free, unplug the dash dimmer connector, and the cruise control stalk plug. Set the cowl aside.

7. Slip the transponder aerial off the ignition lock, and tape your new key butt inside it. A full lockset change from the donor can avoid this issue. Reconnect the battery and you should have startup with your original key in the ignition.

As for programming in other (used) keys, I strongly suspect it would work. It's easiest to get the chips out of the flip type butts; the non-remote keys have the chip in a little carrier that you almost destroy the key to prise out. All the facelift Xantia chips I've seen, are Megamos branded.

[Mandrake]

Thanks addo, that's brilliant

Hopefully it is possible to reprogram a second hand key transponder, then the whole removing the steering cowl and messing with the transponder antenna can be avoided as well.

So I ask again, does anyone know for certain (eg have actually done it) whether a used S2 Xantia transponder key can be reprogrammed to a different car or CPH ?

One other related question - when programming keys to the CPH you obviously need the 4 digit confidential code matching the donor CPH, however if the car being programmed has had the CPH swapped in from another car do you need to enter the VIN number (at the start of the Lexia session) from the donor car before programming the keys, or is it ok to enter the VIN of the car the CPH is now fitted in ?

I get the impression that the VIN number of a Xantia is only used by the Lexia to build a list of ECU models fitted to the car so it knows what ECU's to scan for, but that the ECU's themselves don't contain a record of the VIN number, unlike the BSI in a C5 or later. Which if true means it wouldn't matter whether I entered the VIN of my car or of the CPH donor car as they are identical model and trim.

[citroenxm]

Id just like to add to save you some time, THERES NO NEED to swap areial pickups, they are simply that a Pick Up ONLY.

Only CPH and ECU's can be swapped BUT need to be paired, BUT then a Lexia session is needed to re-match your own key, UNLESS you get the matching key.. Bear in mind though, the Transponder chip is actually in the circular mould of the key blade, and NOT in the big fob...

[Mandrake]

Thanks for that - can I take that as a confirmation that I can program the donor CPH to accept my existing already used keys ? I have one standard key and one RF transmitter key.

Yep, I know where the transponder chip is in the key (hence wanting to reprogram if possible) and I wasn't planning to swap the aerials.

Addo's suggestion to remove the antenna was only to tape the key that belongs to the CPH directly to the aerial while still using the key belonging to the car in the ignition to "fool" the system while doing a temporary swap. I'm hoping to just reprogram the keys with the Lexia and avoid all that tomfoolery

[citroenxm]

You ll need to swap the locks then... sorry I realise what your dooing there then..

Im not sure if the system will work with the two keys nearby, it may get confused. Or it may simply ignore the replacement key if the matched one is present and close enough...

I want to do this with my Xantia HDi, but not to cure any issues, but to put in a later ECU from 2000 or 2001 with cruise control function in it..

[addo]

It only reads the key in the ring; this is a "dumb" system and you may have other transponder keys in a bunch close by. So long as it gets a match it doesn't care how many other keys are "seen".

Similarly I can have several different buildings' passcards in my wallet; I just hold the wallet to the reader and the relevant door opens.

[citroenxm]

Nice one adam.. thats brill.. i wasnt certain.. but i am now

[Mandrake]

Good news people, I can end the speculation and definitely confirm that it IS possible to reprogram second hand, already used S2 Xantia keys for use on a different car. (or CPH)

For the last week I've had a borrowed CPH and engine ECU in the car - because I didn't have the confidential code for the donor CPH to attempt programming the keys I had the steering shroud off with the transponder antenna hanging down - to start the car I had my key in the ignition and the donors key held near the transponder antenna during starting.

It doesn't seem to be possible to just hold the donor key close to the other key with the antenna in its normal place over the ignition barrel - having two different keys in range of the antenna confuses the system so the "wrong" key has to be kept away from the antenna...

Yesterday I got the confidential code so today I attempted to program my two keys (one RF remote, one standard) to the donor CPH - and it worked perfectly, both for the RF transmitter and engine starting.

This means that conversely it would also be possible to buy a second hand Xantia key and program it to a given car, provided that the key contains a transponder and you know the confidential code for the CPH in the car.

Unlike a C5 where the programming process seems to write a permanent change to the transponder in the key itself which can't be undone, the S2 Xantia key programming process does NOT do anything to the keys at all, it is simply the CPH learning the unique codes of the transponders in the keys.

[citroenxm]

I knew a second hand KEY can be programmed to a body computer/transponder immobiliser..

What you cant do is swap a second hand ECU on its own, then program it to your car after..

That has to be matched to the Body Computer, all of this which you have found out.

[Chetiya Dias]

This is a fifteen minute job, done with ignition off. You need a 10mm nutdriver or spanner, and a T20 screwdriver.

1. Lift the bonnet and take the ECU box top off. Lift out the guts. Unclip the ECU plug, and unbolt the ECU from the slide-in plate (10mm heads) - replace ECU and reassemble box/lid. Disconnect the battery.

2. Open glovebox. Remove screws in rubber buffers at top. Remove screw on right side near check strap. Peel up felt and remove screws on left lower side and across the base. Ease the glovebox forward - when all screws are out it will come free readily. Look for the orange airbag wire clipped to the side of the glovebox shell and prise the clip loose. Pull the box out a little further and disconnect the white plug at its rear base. You can now set it aside.

3. Remove the T20 screw now exposed at the upper right of the opening, it holds a white nylon bracket heat welded to the air duct. Push the ducting hard left to free it from the HVAC box and bring the right side forward, then it will come free at the left side locating peg, in your hand. Now look to and see the yellow and black plugs at the front of the CPH.

4. Pull the red tag on the black plug, to the left to release it - it's like the Bitron or cruise control plugs. On the right plug (yellow) you need to gently depress the lock tab in order to slide the locking bar (a black strap) towards the left; the action of hingeing it works like the ECU plug. The CPH is now disconnected.

5. Identify the little ramps on the front edge of the CPH's black plastic mounting tray. With your right fingertips, pull the tray's front lip down whilst using your left hand over the top of the box to push it forwards. Be confident and it will come readily. Slide in the other CPH, reconnect the plugs and (optional) refit the glovebox. I write the immobiliser code and donor VIN on both ECU and CPH with marker pen.

6. Remove the two screws on the steering column cowl that secure the top half - take this off. Now pull the lower cowl half downwards at the front to clear the wheel, then towards you and to the left to clear the rear locating tab (check for a third screw!) and angle adjustment lever. As the cowl bottom comes free, unplug the dash dimmer connector, and the cruise control stalk plug. Set the cowl aside.

7. Slip the transponder aerial off the ignition lock, and tape your new key butt inside it. A full lockset change from the donor can avoid this issue. Reconnect the battery and you should have startup with your original key in the ignition.

As for programming in other (used) keys, I strongly suspect it would work. It's easiest to get the chips out of the flip type butts; the non-remote keys have the chip in a little carrier that you almost destroy the key to prise out. All the facelift Xantia chips I've seen, are Megamos branded.

Hi. I am from Sri Lanka and have a Xantia 2 with 2.0i 16v engine. When I bought this car one year ago the cph was removed by the previous owner due to a cph fault. Suddenly car has not start and immobilizer warning light has come on and when they checked, have found that the cph is faulty. So they had removed the cph and some how with by passing the system started the car. Ever since until last Sunday car started without a issue for the past one year. Any way I wanted to install a cph mainly due to interior lights not working because of the cph is removed. So I bought a cph with the same Texton serial no as the original unit with the remote key of a donor car from ebay but I didn't get the 4 digit code of it. But I got the vin of the donor car. I conected the cph to my car and now it wont start.