BimmerFest BMW Forum banner

2 keys, one works, one not really...

1K views 4 replies 3 participants last post by  joylove 
#1 ·
Hey guys. First time post. I'd appreciate any thoughts and suggestions on my latest issue and I hope I can return the favor down the road. Thanks for your insights.

My wife has a '04 X3 that has been acting up lately. We're due for an upgrade and will likely be replacing the car soon, but I'd like to get this little issue resolved asap, regardless.

While at one time the problem was intermittent, currently her key almost always fails to start the vehicle. Remote lock/unlock/trunk buttons operate fine, all the lights on the dash appear normal when turning the key to 'on', but the engine won't crank until many many attempted turns of the key. One time recently she just held the key in the start position and after about a 7 seconds delay the engine finally started up.

I suspected it may be related to the key so I had her switch to my key for the car, and she's had zero problems ever since. Further trials have confirmed the problem is certainly related to that particular key.

I've read about the EWS/Immobilizer (are these two separate parts that work in concert for anti-theft? Like the one in the key vs one in the dash??), and wondering if there may be a problem with the chip in her key. Thoughts? And if so, is there any repair out there? Will re-initializing the keys help? I can solder thought I wouldn't call myself great at it.

Wondering if I'm destined to purchasing a new key from BMW. I certainly don't like having just one functioning key for the car. She loses things :p
 
See less See more
#2 ·
Random thoughts ...

- don't forget you should have a 3rd. key somewhere (the plastic valet key with a chip that does everything except unlock the glovebox)

- does the metal part of the suspect key look worn, maybe from being on a heavy ring with lots of other keys and doodads?

- the keys cannot be opened up for repairs without ending up with a glued together end result

- I think EWS (electronic watchdog system?) is just BMW's term for the whole immobilizer implementation

- as door locks work the battery in the key should be sufficiently good and charged

- not sure whether reprogramming for the EWS is indicated and if only the dealer can do that at great cost (possible an up-to-date and well-equipped locksmith outfit could do it)

- new key ordered from dealer comes from a central point and after dealer programming costs around $300 I hear
 
#3 ·
I had indeed forgotten about the valet key. Thanks for the tip. Pulled it out last night for that moment when all else fails.

I did carefully inspect the non-functioning key side-by-side with the one that has no problems and there are seemingly no differences. She does carry quite a few keys on her chain...

When I asked about re-initializing, I'm inquiring about something I've never tried nor fully understand. But the process of inserting the key, turning it to 'on', removing key and while depressing the unlock button hitting the lock button three times. I figure it's a pipe dream in terms of actually helping with my problem but something I considered nonetheless. Unsure if I could end up with unintended consequences...

Thanks for the reply, Supercourse.
 
#4 ·
.... I figure it's a pipe dream in terms of actually helping with my problem but something I considered nonetheless. Unsure if I could end up with unintended consequences...
Yes, the programming for the door locks (and seat adjustments, etc.) is distinct from the programming for starting the vehicle.

With electronics involved, it is conceivable that re-doing the perfectly working door locks might stir the start capability back into action. But I sort of doubt it.

I suppose you could end up with a totally non-working key if not done correctly, or if there is something flaky inside the key.

As you may know, the key also stores information about your car that the dealer retrieves in the key reader.

Might be worth dropping by and seeing if they can still do that with it.
If it works, no useful conclusions to be drawn.
If it doesn't, it would tend to add weight to the faulty chip theory.
 
#5 · (Edited)
There is a significant difference between the remote entry and the immobilizer system, the two systems are totally separate, even though they use the same key.

Immobilizer uses an RFID 128 bit rolling code partially obscured chip in the key to determine if the RFID chip is valid and enable the fuel pump and the starter motor. The system is very secure. There are 10 valid chips for each car, and to obtain the next chip in the sequence you need to order it from Germany in a new key with proof of ownership. If you peel the sticker off the purse key, you will find a chip.

The remote entry and alarm is more simple. It too uses a rolling code and the key battery is charged which you drive. Should the code become unsynched for some reason such as low battery or more than 1000 accidental presses you can relearn the keyless entry part using the button press sequence you found.
 
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top