Immobilizer problems in a Xantia

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Azrael
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Immobilizer problems in a Xantia

Post by Azrael »

I'm the unlucky owner of a s.h.-bought Xantia s2 1.8 16v with an auto transmission. Lately the immobilizer has started to be triggered randomly and the only way to fix that has been to tow it to a local repairman to have the key re-paired.
It's getting really expensive and i can no longer afford this.
So here is my question: is there a way to completely disable the immobilizer? If yes, can this job be done by me, a regular mechanic or only by the dealer?
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Re: Immobilizer problems in a Xantia

Post by CitroJim »

The short answer is no but the longer answer is yes, possibly and an even longer answer would be to correct the fault.

The immobiliser is not at all straightforward to bypass and the only way is to have the engine ECU reprogrammed to remove the security feature. Some ECU specialists can do this but it is neither easy nor cheap.

Do you have two or more keys? If so, do all keys fail at the same time? Also does the central locking from the remote fob (plip) fail too?

If it is happening on one key only or you have only one key, buy a new blank from Citroen (part No. 9926 HA) at £17 have a local good locksmith cut it for you and then have it programmed.

I'm sure there is a Lexia owner near you who can do the programming for you. Have a look at the list in this thread for someone close by...

For the immobiliser or transponder to fail like this is very rare indeed.
Jim

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Re: Immobilizer problems in a Xantia

Post by Azrael »

I have just one original key (chipped) and 2 recuts. The can be paired without any problem so it appears that the transponder and the antenna are functional.
The plip is non-functional (the board is there in the key but the external buttons are missing and when shorting the points on it nothing happens - yes, i know, not the best solution, but i bought the car from a scrapper since it was the only one i could afford), but it was like that when i bought it - with a custom alarm/remote. The problem isn't with the key, it's with the ECU and/or the wiring - in the last 2 months if i don't start the engine daily to top off the battery it will lose the pairing.
Yes, i have found locally a cheap service shop that is pairing the key for just £20, but the towing costs me over £80 and a lost day from job, and i simply can no longer afford that.
I hoped that it would have been a simple fix, like in the old models.
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Re: Immobilizer problems in a Xantia

Post by CitroJim »

That's interesting that running daily will keep the keys paired... It's almost as if there's a back-up battery somewhere in the system that's supposed to maintain the transponder memory not doing it's job - something like a CMOS battery in as PC. Never been aware of one though... I thought any memory was EEPROM and safe from voltage fluctuations. After all, the battery can normally be disconnected for a good long while with no ill effects.

For the cost of one re-pairing and one towing you can get yourself a Lexia and do the key programming yourself as many times as you need for free afterward... It's a very simple job. It does not cure the root cause but it solves the problem with a workaround...

We need some enterprising soul to break open a transponder and CPH and see if there is a back-up battery in there...
Jim

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Re: Immobilizer problems in a Xantia

Post by Azrael »

Yes, it though about buying a Lexia myself, but you also need a laptop to make it work. Unfortunately, no money for a laptop.
What's weird is that when i bought it the car was unpowered for at least a month and it fired just fine. During the summer i could leave the battery disconnected for days and this wouldn't happen. My guess is that there is a bad / corroded / broken contact somewhere in the wiring loom. I, and my mechanic, have searched for it and couldn't find it.
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Re: Immobilizer problems in a Xantia

Post by myglaren »

Have a look here.
Will may still have some suitable laptops at reasonable prices, made for the job as they have XP on them.
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Re: Immobilizer problems in a Xantia

Post by Azrael »

Sorry, i'm heavily in debt now, no way i could pay for a laptop. I was trying to get my scrapper of car fixed and try to find a better, stable job. If that fails because, as the mechanic thinks now (he made the pairing again but the ECU is no longer detectable by Lexia), my car is dead then i'm in deep shyte.
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