E53 key programming - strange problem
 

I had only one key for my X5 so purchased a blank , had it cut , purchased another working BMW key and swapped the innards.
Programmed it - 'hold UNLOCK and press LOCK key 3 times ' repeat with new key etc .
I now have a spare key that will unlock and lock the doors either manually or remotely , it will turn on the ignition but then the immobiliser will not let me crank the engine !
However if I start the engine with the original key , turn it off and insert the new key it will let me start the engine as often as I want until I open and close the door and then it won't turn the engine over again !
Not a lot of good as a spare key if I need the original to make it work LOL.

Anyone any ideas ?

You need to go to the dealer and have them order you a replacement key that is specifically coded for your vehicle. Take your title with you, along with proper identification. It should take a couple days for the key to be sent to the dealer. As you discovered, you cannot do this yourself with the parts from a remote that was not originally meant for your vehicle.

:iagree:Simple to program it to open/close the doors but it needs to be programed to speak to your ECU. Your only option is to buy a new key from the dealer which will come already coded to your car. Mine was about £100 all in and only takes 24 hours from order to driving away with your new key.

This thread happens every time someone buys a blank key and has it cut... never works. The key has to be ordered by VIN, and there really is no way to make key from blank work...

Decided it is the perfect key to give to my wife - she can open the X5 but not drive it !
She has her own E46 anyway !

Maybe the perfect key to stick in a box hidden under the X5 in case you lock your keys in it at some point... especially so since it can't start it.

That's a good idea !

Notice you live in New Orleans - been there once or twice - a friend of mine lives in Slidell just the other side of 5 mile bridge on Interstate 12 .

Ok,

here's a bit of a strange one..

I have the 01...

my ORIGINAL key just went from working fine, to doing exactly that....

why??

Because it lost the coding between ECU and key?? Not so strange, it happens quite a bit with electronics like this!! I recall the Range Rover used to do this a LOT and cause huge problems for owners who were immobilised due to the complcated way of getting it going again. This is likely a dealer recode in your case.

Just called my local dealer (whom I will NOT name, for their own protection - they're REALLY an excellent group, and offer outstanding service).

Anyway, the service dept person (young gal) tries to help me..

me: "Hi, I'm calling about my '01 X5, having trouble with the key"

her: "I'll be happy to help you"

me: "my key will lock/unlock the doors fine; it won't start the engine"

her: "maybe you need to replace the battery"

me: "already did that - -but remember, it opens/closes doors, just won't start the engine"

Her: "oh... the battery is just weak. get a fresh battery."

me :dunno: "really??"

her: "yes, it is just a little weak.. It takes a stronger battery to power the starter motor than to just unlock the doors. The engine is a lot bigger than the doors."

me: :yikes: "Are you blonde by any chance?"

Anyway, I chatted with one of their mechanics who happened to know the system pretty well.

According to him, there are two completely separate systems in the key. One is the door lock/unlock transponder. It has a large battery (which can be replaced, but he claims isn't recharged). The second is the engine lockout/security system.

ONLY the engine lockout system is charged in this process. EVEN IF your key were left sitting for a time you could stick it in the ignition, let it sit 30-40 seconds, and it would have recharged enough that the chip would fire up the engine.

I kind of disagree with the theory that the remote door lock/unlock circuit isn't charged, because I've seen it go from NOT working to working on one of my keys, after having driven around the mountains for a few hours with the key in ignition... but maybe it was just recharged by the fresh mountain air, and not the electricity? :dunno:

At any rate, i'm going to open up the unit again and see if I can find something cracked.. perhaps I dropped the key and cracked something?

I do board-level repairs all the time, so will magnify it and check out...