Wierd key issue

[Littlerascle]

So I checked most all of the key fob problem posts and I don't see one that matches my problem.

I have one key that works fine. I have a second key that will lock and unlock all the doors turn the accessories on but simply won't turn the ignition on.

However if I use my good key to turn the car on when I turn the car off I can use the second key for a few moments and it will start the car. But after a few minutes the second key goes back to only locking and unlocking the car and turning on the accessories.

What gives?

2003 Z4 3.0

 

[sw4nny]

Wild stab in the dark had a similar situation with a celica .
Really dont know if this will help.
Put both keys on same key fob.try the keys see what happens ,maybe immobiliser problem or key wear.
Never got to the real issue,but keeping keys together meant
Everything worked .
No idea why ?

 

[Smartbear]

Sounds like the immobiliser doesn’t work on the 2nd key.
Rob

 

[srhutch]

Sounds as if somebody might have had a blank cut as an emergency (to get in the car) but either not had it programmed of the key has no immobiliser chip.

Have you tried opening up the key?

If it’s original you can’t open it as they are glued together. If it’s a aftermarket key then you should be able to open it easily.

 

[colb]

Yes the key that isn't starting the car has not been coded, if its aftermarket type it may not even have the chip inside the key fob end. If its aftermarket and can be opened, have a look to check if there is a chip in thre, if there is then it needs coding. The fact that it works immediately after using the new key is that the EWS remembers the codes the first good key used and transmitted to the car for a few seconds after its been used. If you have a AK90 key coding machine you could check the duff key for a transponder being inside without having to take it apart. AK90 is not very user freindly for coding keys, I had no success and ended up getting a mobile locksmith to code it but he had to do itn using his high specc machine and read the eprom chip on the circuit board of the ews module. I paid £120 for the job using my supplied key which had the blade cut already.

 

[Littlerascle]

Thanks guys I'll check into it as soon as things get back to normal. Funny thing, it's my dad's car and he is the original owner. He doesn't remember getting a new key...

 

[colb]

Post a picture of the problem key so we can id it as original or aftermarket. Cover the blade with paper to block the cut pattern when you take the photo.

 

[ph001]

Cover the blade with paper to block the cut pattern when you take the photo.

....can’t be too careful these days eh!