Immobiliser

[keiththo]

Is anyone aware how the immobiliser works ?

My car (less than 18 months old and used regularly) was reluctant to start a few weeks ago, the starter motor was turning but the engine would not fire. It did eventually start and I drove to the Porsche centre but nothing showed.

Does the immobiliser inhibit the starter motor or does it just stop the engine from firing by cutting the fuel supply or HT maybe ?

When I took the car to the Porsche centre I gave them the spare key which I'm continuing to use. Just thinking that the battery in the original key may be low on volts and therefore causing the problem ?

Any thoughts anyone ?

Keith

 

[Richard_Hamilton]

It inhibits cranking, ignition, and fuel supply. The key battery shouldn't affect it. There is a transponder pill for the immobiliser in the key head, which isn't battery powered. The transponder pill also controls the ignition lock. The battery only powers the radio remote.

 

[keiththo]

Thanks very much Richard.........the mystery continues.

 

[Buddy]

Keith, you say that it has been working using the spare key but have you tried again with the first key? If the problem only exists when using the first key then there must be a fault with the transponder pairing to the car, while it may be possible that the fault is with the car I would presume that it is more likely to be with the transponder in the key which should be covered by your warranty.

 

[keiththo]

Hi Kevan, yes I have used the original key again and it worked but it seemed a bit slow to unlock the car which made me think the battery may be failing.

Having used the spare key for a few weeks perhaps I should go back to the original to see if it's intermittent.

Keith

 

[Buddy]

Hi Keith, I think you need to assess when the fault occurs etc but if you have both with you the car may recognise the transponder of the second key in your pocket, so it's necessary to prove out whether the key transponder has a fault and get a replacement under warranty, they probably won't wish to acknowledge such a fault as it is pretty unlikely but when the car works fine with the other... when all expected causes are examined and found not to be then however unlikely the alternative it can be the only cause but it is necessary to prove, it may be a case of the garage pairing the problem key to the car or may be a fault with the transponder as the most likely cause, there may be some other cause being in the pairing in the car systems, good luck with this but best to get it sorted under the manufacturer's warranty rather than later when it may be under the extended warranty and they will probably say that you should have got it cleared on the original warranty, extended is an insurance type warranty so may be a little bit more problematic to get to pay and a replacement key comes in at around £300+!

 

[keiththo]

Hi Kevan I'll look at this again but given what Richard Hamilton said about the immobiliser inhibiting cranking I'm not sure it's anything to do with the key given the starter motor was turning.

 

[Buddy]

Possibly Keith but it could be that the pairing of the key to the car was effectively incomplete, whether by a fault in the operation of the process or a fault in the transponder, it's well worth proving if the key has a fault and maybe getting it corrected. In checking it out then you may find that you now have no problem in which case it is just an intermittent problem which has gone away.