Bad solder joints in the key will give you the symptoms you describe.

Try this:

Lock door with key in the cylinder and immediately after removing the key try to unlock the car with the fob.

Also do the reverse. Unlock with key and try to lock with fob.

If you can remote lock/unlock immediately after a key lock/unlock it's almost certain it's bad solder joints in the key fob. (both of my keys did exactly like you describe and I could get them both to work immediately after a keyd use for up to 20-40 seconds and not after).

I opened up my keys and reflowed the solder and they both worked 3 years until i lost one and the other stopped working remotely again.

I can't risk reflow my only key so I'll be ordering a new one soon and then I'll open up my current key and reflow the solder again.

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2011 E70 • N55 (me)
2012 E70 • N63 (wife)