Hi I am thinking about replacing the battery in my key fob for my 2002 BMW 330Ci E46. I vaguely remember reading these fobs have RFIDs in them to open the car. Not sure if this applies to both the keyless and keyed entry. Say I mess up somehow and fry the circuity for the keyless entry… will the key still work to open the door manually? Anything else to worry about? Thanks!
Never mind
Edit: yeah, who knew. Just replace it
The keyless entry battery is soldered in place and the key handle is glued shut. The easy solution is to replace the key.
The link below shows information for do-it-yourself key battery replacement.
DIY: E46 Key Battery Replacement (bimmerforums.com)
1 Like
Well who knew?
@Nevada_545 Easy … but expensive… IIRC when I called the local bimmer dealers a couple years ago it was going to cost ~$300+. Definitely not throwing away that much money when I can fix it myself. Still have the same question though - if I mess up will the key still work? I’ve watched a video on replacement and it looks within my pay grade.
@bing Also what’s the who knew thing? So many posts edited/deleted I don’t follow. 
The door should still unlock with the key, the lock cylinder might need to be lubed though.
It’s just a normal key fob is easy, but obviously Nevada had the unique issues with this one. So the who knew was related to who knew it was that complicated for a simple battery change on conventional fobs. That’s why I just deleted my comment on how to do it, and the link Nevada provided covered it all. Cheers.
Don’t you have 2 key fobs ? If you break one the other should still work . Or if you have a Batteries Plus near you call and see if they can put a new battery in for you.
I believe the keyless entry transmitter in in the key handle, no separate fob.
The original keys can’t be easily disassembled like most others, the housing is glued together. The battery was supposed to be charged via induction from the immobilizer antenna, however that battery is 22 years old.
Replacement keys are available online, make sure you can get the new key cut.
1 Like
No experience with BMW key fobs, but be careful, & wear eye protection & face shield if soldering directly to a battery. It could explode if overheated. Me, I have a pro-type temperature controlled soldering iron, so I’d risk it if could save $275 compared to a new oem replacement as a diy’er job. If I could find a new aftermarket replacement key for $100 or less , I’d probably go that route. Note: There may be a significant reprogramming fee at a BMW dealership if you elect to simply replace the key.
1 Like
I went to batteries plus once to have a new battery put in my shaver. They used what looked like a little spot welder for the contacts. A couple quick sparks and all done. Some reassembly required.
1 Like
Everything went great guys, thanks for the help! I’m lucky I didn’t cut off my arm trying to cut open the key fob it took a gorilla amount of force to open it up. Curious anybody know how Batteries Plus would open up one of these?
My guess - they wouldn’t.
1 Like
+1
Probably just like in car battery’s in fender wells and things like that, they have exclusions and don’t do it…