C5 2002 Key recode?

Pjsprojects · Post by **Pjsprojects** » 14 Sep 2010, 22:33

I have just bought a nice HDi C5 but the remote flip out key buttons won't lock or unlock the car and even though the ignition lights come on the car won't start.
The spare none remote key works fine and the car starts first time so seeing as i have already replaced the remote battery does it need some sort of recode and if so how do i do this?

citronut · Post by **citronut** » 14 Sep 2010, 23:32

sounds like you need a LEXIA setion, check out the LEXIA map for the nearest forum member with one in the usefull links section on here,

regards malcolm

Post by **Paul-R** » 15 Sep 2010, 09:54

If the key won't start the car then, as Malcolm says, it sounds like it needs re-pairing to the car using a Lexia.

Once it's been paired getting the remote locking to work is done simply by putting the key into the column lock, turning it to "ignition" and pressing down one of the lock buttons on the fob.

citroenxm · Post by **citroenxm** » 15 Sep 2010, 10:07

Paul,

The Re-sync-ing of the key in the colum appears NOT to work this way in the C5.
Ive a customer with a C5, the Fob does start the car, and he has apparently had the key checked, it is giving a signal out, but I cannot for the life of me get it to Talk to the Car to unlock or lock the car....

Unfortunally he has no Key Code to go with the car either, so I cannot re-program the key...

The lexia will work only with a Key code...

Does anyone know if the Locking ECU can forget the Key completely???

Ive told him to goto the Dealer and ask them how juch to recover the Key Code.

Incidentally, the key did lock and unlock the car when he first had it...

Paul

Post by **Paul-R** » 15 Sep 2010, 10:24

citroenxm wrote:The Re-sync-ing of the key in the colum appears NOT to work this way in the C5

Not convinced about that. See my reasoning as follows...

citroenxm wrote:Ive a customer with a C5, the Fob does start the car, and he has apparently had the key checked, it is giving a signal out, but I cannot for the life of me get it to Talk to the Car to unlock or lock the car...

If he has two keys (with button fobs) and one works that's strange, for sure.

However if he has only one key, as I suspect, and he's SURE that the remote locking part is transmitting thern this points to a fault with the receiver on the car surely?

citroenxm wrote:Unfortunally he has no Key Code to go with the car either, so I cannot re-program the key...

Yes, as you say later he has to get that from the dealer.

From my experience that's quite easy. You need the car's logbook showing your name as keeper and some proof of identity and payment of £20. A few days later all the security details of the car arrive (inluding locking wheelnut key if fitted)

citroenxm wrote:Does anyone know if the Locking ECU can forget the Key completely???

Don't know for sure but I would have thought unlikely. Much more likely for the receiver part to malfunction.

citroenxm wrote:Incidentally, the key did lock and unlock the car when he first had it...

Even more I suspect the receiver circuitry!

Post by **RichardW** » 15 Sep 2010, 12:03

If the correct battery disconnect procedure is not used, the the BSI can forget the remotes (happened to my Dad's Xsara when he had the alternator replaced

). The only way back is via a Lexia with the key code. Any Citroen dealer should be able to supply the code for not too many pennies - the supplying dealer may have it on record and release it FOC, but then again....

Post by **Paul-R** » 15 Sep 2010, 13:59

But surely in that case the key would not have started the car? That way you'd need the Lexia for sure.

THELABMAN · Post by **THELABMAN** » 15 Sep 2010, 18:53

Sorry to slightly hijack the thread guys......

I've only got the one key that came with my C5 and it's the one on the remote control fob, having read some of the info on here and other threads am I in for big trouble if I have to change the battery...

I do have a credit card sized card with a key code on it, will this allow me to purchase even a non-remote key from the dealer.

Thanks and again sorry for slightly hijacking this thread..

Peter

Post by **myglaren** » 15 Sep 2010, 20:00

I removed the battery from my key experimentally and nothing bad happened

It was disconnecting the car battery that was the problem - there is a sequence and ignoring it can lead to - unpleasantness

the car catching fire was just a coincidence

citroenxm · Post by **citroenxm** » 15 Sep 2010, 20:58

DO NOT GET YOURSELFS confused!!

A buggered FOB will have no effect on starting the car, or unlocking the ECU, as the key blade has its own Transponder Chip in it!!

This is why my customers key still starts the car but wont open it...

The Fob locks and unlocks the CAR not the ECU...

So even if you kill your Fobs, you still be able to drive your car...

Paul

Post by **Paul-R** » 15 Sep 2010, 21:35

Just to throw the cat amongst the pigeons I changed the batteries on both the C5 and Xsara a few months ago and all I did was disconnect the old ones and then put the new ones in.

No special procedure and they both restarted straight away. Can't remember whether I had to resync the remote locking or not though.

citroenxm · Post by **citroenxm** » 15 Sep 2010, 21:46

Paul-R wrote: No special procedure and they both restarted straight away. Can't remember whether I had to resync the remote locking or not though.

Ofcourse they will, thats what I was saying above the Fob BATTERY does NOT power the transonder chip! Thats a completely independant thing in its own right....

Paul

Post by **Paul-R** » 15 Sep 2010, 22:35

It was in response myglaren's post!

myglaren wrote:It was disconnecting the car battery that was the problem - there is a sequence and ignoring it can lead to - unpleasantness

Post by **RichardW** » 16 Sep 2010, 07:34

Steve was talking about taking the CAR battery off, not the fob battery. If this is not done carefully, allowing the BSI to go to sleep, and giving it a cuddle and allowing it wake up gently

it can throw its toys out of the pram, a symptom of which is being unable to lock / unlock the car with the remote. If really bad it can totally bugger the BSI which then needs replacing....

Qwality design, init

citroenxm · Post by **citroenxm** » 16 Sep 2010, 08:13

Thats interesting Richard, Im thinking thats possibly whats happened with this C5 of my customers...

Lexia shows a faults in the BSi, and the symptoms are when you first use the car all insturment lights work fine... untill you switch on the sidelights, then all warning lights, thats seat belt, manegment lights, indicator lights etc etc all stop working... the things them self work, you can hear the indicators work, the lights work, just not the warning lights.. also speedo, revs and fuel/temp guages still work....

I cannot find directly the cause, just a BSi fault..

From what you say, I wonder if someone has abused the system without knowing what they are dooing with sensitive electronics...

Paul