Inside there is a remote key battery that can run out of useful life. If the battery runs out, the Keyless Entry to be not functioning, so we must open the lock through the keyhole in the door.
It often happens, when after replacing the battery, the remote become dysfunctional. This is because when the batteries are disconnected from the remote, there's only 60 seconds to immediately replace them with new ones.
When the 60 seconds missing, then the remote should be synchronized with the existing security system in the car. Previously, every time the need to synchronize the remote. Line up at the official workshop quite a lot of time.
We can do its own synchronization with a fairly easy and does not require any tools. Here are the steps:
1. After the new battery is replaced, we headed for the car, unlock the door using the key.
2. Once entered into the car, make sure all the doors closed.
3. Insert the ignition key. Turn key to position-1 (acc), leave for 5 seconds, then return to position-0 and remove key.
4. Immediately after the key in remove, press the UNLOCK button on the key. Permanent press UNLOCK button for 10 seconds. For 10 seconds, press the LOCK button 3 times (not too fast). After about 10 seconds, remove the UNLOCK button.
Then, after the UNLOCK button is released, the door knob lock will lock and unlock by itself, indicating successful synchronization process.
5. To synchronize the second key (reserve), immediately repeat the number 4 above within 30 seconds of the first key from the ignition key removed. (Must be done quickly).
If the process is unsuccessful, to repeat the synchronization have to wait about 30 seconds, and do not perform with the door open.
These tips apply to almost all models of BMW cars that use the Keyless Entry (Remote). (Series 1, 3, 5, 7, X3, X5, etc).
So tip, may be useful.