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BMW 3-Series (E90 E92) Forum > BMW E90/E92/E93 3-series General Forums > General E90 Sedan / E91 Wagon / E92 Coupe / E93 Cabrio > my key FOB is dying...can I revive it?



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      12-21-2013, 01:27 AM   #1
slowbutsure
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my key FOB is dying...can I revive it?

I have been using this california (non-comfort access) key fob for a while and it has worked well then today it can't start the engine. It seems to turn on the electronics of the car as usual but won't start the engine. It unlocks, locks, opens the trunk ok. I tried my spare and it is able to turn the engine. Should I just change the battery inside? Any recommendations? Thank you in advance!
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      12-21-2013, 06:06 AM   #2
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The car should tell you when the comfort access key reaches the minimal batter level. Even if you're not getting that indicator it is worth the $5 and a trip to Radio Shack.
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      12-21-2013, 08:25 AM   #3
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+1 above. Sounds like you've never changed that battery and your car's an '07? 6 years for that button cell's a good run.
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      12-21-2013, 08:33 AM   #4
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OP says its a non ca fob...

If it is a battery problem, are the non ca fob rechargeable batteries replaceable?
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      12-21-2013, 09:09 AM   #5
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Non-CA Fobbs to not have batteries- you need to replace it.
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      12-21-2013, 09:20 AM   #6
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      12-21-2013, 10:13 AM   #7
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Quote:
Originally Posted by Dark_Knight_335
Non-CA Fobbs to not have batteries- you need to replace it.
Well, they have a battery, but not supposedly user replaceable. I think, however, there's a RFID type of chip in there that authenticates to the car allowing it to start. Those chips are not powered. That's how it worked on my e46 and e38 anyway. The chip looked like a little piece of black plastic, and you could move it to a new key if your old key got damaged.

Basically the remote "lock/unlock" functions and the "start the car" functions are two different systems enclosed in the key casing.
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      12-21-2013, 10:51 AM   #8
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Quote:
Originally Posted by CombatNinja View Post
The car should tell you when the comfort access key reaches the minimal batter level. Even if you're not getting that indicator it is worth the $5 and a trip to Radio Shack.
but it's not comfort access though. I've looked inside and it does have a battery, however, it does open and close the door ok, it just wont start the engine. Something to do with the chip inside the actual key?
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      12-21-2013, 10:54 AM   #9
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Quote:
Originally Posted by Dark_Knight_335 View Post
Non-CA Fobbs to not have batteries- you need to replace it.
this is a california key fob, non comfort access.
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      12-21-2013, 11:09 AM   #10
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Here's some information I found

http://www.bmwgm5.com/E46_EWS.htm
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      12-21-2013, 12:06 PM   #11
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Quote:
Originally Posted by slowbutsure
Quote:
Originally Posted by Dark_Knight_335 View Post
Non-CA Fobbs to not have batteries- you need to replace it.
this is a california key fob, non comfort access.
Haha- had to read through this a few times before I "got it." *Googles "California key fob."
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      12-21-2013, 04:52 PM   #12
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WTF is a California key fob?
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      12-21-2013, 05:10 PM   #13
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Quote:
Originally Posted by CombatNinja View Post
WTF is a California key fob?
good question...It's been mentioned a few times but I don't really know other than I live in california and the key is CA fob. sorry
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      12-21-2013, 05:49 PM   #14
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Silly narcissistic Californians

When people talk about CA key fobs they mean comfort/convenient access, not California.

When you find out how much the dealer will rape you for a new one, you'll wish it was a Kentucky key fob...
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      12-21-2013, 06:05 PM   #15
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So the OP has a CA key fob but no CA in the car? Is this real life?
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      12-21-2013, 06:11 PM   #16
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Quote:
Originally Posted by CombatNinja View Post
WTF is a California key fob?
Sarcasm?
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      12-21-2013, 07:05 PM   #17
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Quote:
Originally Posted by NormE91 View Post
Silly narcissistic Californians

When people talk about CA key fobs they mean comfort/convenient access, not California.

When you find out how much the dealer will rape you for a new one, you'll wish it was a Kentucky key fob...
Thank you for the clarification. It's a Non-CA fob. Yes, it seems I will get raped because I don't know how else to get a spare going.
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      12-21-2013, 07:51 PM   #18
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Quote:
Originally Posted by NormE91 View Post
Here's some information I found

http://www.bmwgm5.com/E46_EWS.htm
Thank you NormE91! explains things a bit
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      12-22-2013, 03:05 AM   #19
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I think you really need to order a new key fob if it's non CA.
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      12-22-2013, 03:51 AM   #20
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If it has a cover you can open to see the battery .

If it has a cover you can open to see the battery
and the battery is replaceable it has to be a Comfort Access Fob.
And you can get cr2032 batterys for about 3 bucks each at
a drug store or for less than a dollar on Ebay.
There was a procedure somewhere on how to replace the rechargeable battery in the non ca keys . The bmwgm guy was
saying the problem was seldom the battery though and even
if the battery is flat the fob is suppose to start the car, if you put it in the fob slot. (for either a CA or non CA Fob)
Suggest reading the manual doing a vin check for options
at one of the free websites and verifing if you have comfort
access or not.
If you don't have a manual you can download one for free
at bmwusa.com

Also the old style blade that is in the keyfob needs to be in it
for it to work for starting the car I believe.
Very hard to be of any help without a accurate description
that we can all understand in BMW terms.

Last edited by ctuna; 12-22-2013 at 12:54 PM.
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      12-22-2013, 02:28 PM   #21
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You CAN replace the battery in the non-Comfort Access key fob. You need to be willing to do some surgery though. I'll put up some pics if requested.

You'll need to cut along the seam around the perimeter of the FOB with a razor blade. Take your time. and be very careful not to penetrate too deep, you can easily damage the PCB inside. I actually knocked a capacitor off and scraped a couple of traces, but I was able to replace the cap (and the traces were not badly damaged). The battery is a Panasonic VL2020 with welded tabs which you will have to de-solder from the PCB. I found a similar battery at Digikey.

http://www.digikey.com/product-detai...P081-ND/119936


I was not able to find the exact same pin configuration for the battery (haven't looked very hard yet), but I think that one could be made to work.

So solder in the new battery and glue the housing with some black CA and you'll be good to go.

http://www.amazon.com/IC-2000-Rubber...rubber+ca+glue

I have not received my new battery yet but I did remove and re-install the old one just to be sure that it would still work and all is good

Good luck!

Last edited by Biz92; 12-22-2013 at 02:33 PM.
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      12-22-2013, 09:13 PM   #22
slowbutsure
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Quote:
Originally Posted by ctuna View Post
If it has a cover you can open to see the battery
and the battery is replaceable it has to be a Comfort Access Fob.
And you can get cr2032 batterys for about 3 bucks each at
a drug store or for less than a dollar on Ebay.
There was a procedure somewhere on how to replace the rechargeable battery in the non ca keys . The bmwgm guy was
saying the problem was seldom the battery though and even
if the battery is flat the fob is suppose to start the car, if you put it in the fob slot. (for either a CA or non CA Fob)
Suggest reading the manual doing a vin check for options
at one of the free websites and verifing if you have comfort
access or not.
If you don't have a manual you can download one for free
at bmwusa.com

Also the old style blade that is in the keyfob needs to be in it
for it to work for starting the car I believe.
Very hard to be of any help without a accurate description
that we can all understand in BMW terms.
So did some research...seems the transponder chip in the fob is the culprit. At it's current state, it can still lock, unlock doors, trunk so it must have a battery left. I have a feeling I will be raped for this one though. Anybody work at BMW dealer?
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