E46 2002 Cannot resync key

[aidasb]

Hello guys,

I know there has been numerous threads about resyncing/reprogramming the key to the car. But no matter of how much tutorials I have read, nothing seems to work:

A bit info: I have 2 keys, both of them can start the car (not always, but after taking it out and putting it in a few times, it starts to work). Now only 1 key is synced with remote lock and unlock, lets call it key A. The other one - I just can't get it to be synced, lets call it key B.

Currently this is how it works. I unlock the car with key A, get in the car, and use key B to start the car. I can start the car with key A, but that requires many ins and outs to the ignition. I could leave my key B safely at home, but usually it's a burden to get key A start the ignition.

I have tried this one https://www.bimmerforums.com/forum/s...-reprogramming and many others. Doing these methods I can get the key A to resync (and I can see doors locking and unlocking). But the key B just can't get synced.

What could it be? A dead battery inside?

[MarcoZandrini]

There are 2 separate electronic systems in the keyfob. One is for the lock/unlock system. That function is powered by the battery in the key. The second system is the anti-theft system. The electronics in the key are powered by the black ring antenba that surrounds the ignition switch. The keys’ 2 electronic systems don’t know the other exists. So, the “syncing” process aligns the anti-theft electronics in the key with the car’s anti-theft system called EWS.

A key’s inability to lock/unlock the car is caused by either a bad key battery or a electronic problem in the key.