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Discussion Starter · #1 ·
Good afternoon!

I recently purchased a 2003 BMW 325i (e46). First time BMW owner here :). It's in practically mint condition, with the exception of the key fob.

The key will lock/unlock doors and arm/disarm the alarm, but the remote does not. I read through this entire thread, but was not able to find a solution that directly relates to me: http://www.bimmerfest.com/forums/showthread.php?t=152230

When I lock the car with the key, the fuel door does not open. I attempted to reprogram the key using the method listed in the thread I posted above, but no go. I double checked any and all fuses that may be related to key fob issues, but again, no go. All related fuses are completely intact. I've seen some videos of people replacing the battery, and was wondering if I should try that? I'm a trained IT Professional, and I used to install custom sound systems in cars. I know how to solder.

I'm wondering if:
A) There are any more troubleshooting/diagnosing I should attempt before replacing battery.
B) What dangers are included with battery replacement? I only have this one key for the BMW.
C) Will replacing the battery fix my key fob remote entry issues?

Any and all help/suggestions are appreciated._a__a2_
 

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Discussion Starter · #3 ·
UPDATE: I've replaced the battery. I've soldered the new battery into the key fob. It clearly works, as it starts the car and unlocks/locks the car via key. Though I tried to reprogram the key via several methods found in user manuals and forums, still no go. Remote functions on the key fob do not work. I've checked fuses relating to the key fob, all are good. Any ideas? Or do I just need a new key?
 

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Just for your info, the key fob has 2 separate circuits. One is for the remote lock/unlock functions. That circuit is powered by the battery. The ignition interlock function is powered by a ring antenna on the ignition switch. That ring antenna also recharges the battery.

Do you have another key with which you can check the lock/unlock functions? These functions are managed by the General Module (GM5) that sits above the fuse box above the glovebox. It's full of relays that can and do go bad.
 
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