BimmerFest BMW Forum banner

1 - 10 of 10 Posts

·
Registered
Joined
·
10 Posts
Discussion Starter · #1 ·
Hi all,

2008 E91 Touring and having problems with the Key FOB battery. I have read forums and threads so to clarify -

  • No comfort access (key needs to be in ignition slot in order for car to start)
  • Back of key can be opened and battery can be replaced - 2032 Lithium battery

I've owned the car for 13 months now and probably replaced the battery 10+ times.
Every time I replaced the battery the key will work for an average of 3 - 4 weeks then it dies.

The batteries were bought at different stores (brand new) and tried different brand names. Same thing.

Any ideas why the battery dies so quickly? Or is there something wrong with the FOB itself?

Thank you.
 

·
Registered
Joined
·
3,384 Posts
A non-CA fob does NOT usually have a port that allows access to a 2032 battery...the non-CA fob uses a RECHARGEABLE battery (not 2032) and has to be cut open to gain access to its battery.

Does your car have a door handle with parallel ridges on the top surface? If it does, you have a CA car with capacative sensors in the handle, and your need to insert the key into the dash slot is NOT the way to should normally behave.

In any event you should NOT have to replace battery in the CA fob that often...once every two years is typical interval. Furthermore, BMW advises to NOT put the CA fob in the dash slot, except for very special circumstances. Perhaps its use in the slot is contributing to its problem?!
 

·
beemlyfe
Joined
·
683 Posts
A non-CA fob does NOT usually have a port that allows access to a 2032 battery...the non-CA fob uses a RECHARGEABLE battery (not 2032) and has to be cut open to gain access to its battery.

Does your car have a door handle with parallel ridges on the top surface? If it does, you have a CA car with capacative sensors in the handle, and your need to insert the key into the dash slot is NOT the way to should normally behave.

In any event you should NOT have to replace battery in the CA fob that often...once every two years is typical interval. Furthermore, BMW advises to NOT put the CA fob in the dash slot, except for very special circumstances. Perhaps its use in the slot is contributing to its problem?!
OP clearly stated that it's not comfort access..

OP, you have tried basically every variable. It's the fob itself imo.
 

·
Registered
Joined
·
3,384 Posts
OP clearly stated that it's not comfort access..
So he should NOT FIND the 2032 battery in it! He also stated, "Back of key can be opened and battery can be replaced - 2032 Lithium battery" and a non-CA fob has no battery door and has no 2032 battery in it. The combination is NOT in a non-CA fob!
So what is the truth about his car, CA or not CA car?!

It's kinda like telling me "I have a 4 cylinder 335i"...not possible!
 

·
Registered
Joined
·
4,147 Posts
Using a conventional nicad or Li button battery in a circuit designed for charging a rechargeable fob battery (induction charging) is NOT recommended. In fact, it could be dangerous!

I have read that some people have managed to open the NON-CA FOB and replaced the dead rechargeable button battery with a new RECHARGEABLE battery ... GOOGLE is your friend!
 

·
beemlyfe
Joined
·
683 Posts
So he should NOT FIND the 2032 battery in it! He also stated, "Back of key can be opened and battery can be replaced - 2032 Lithium battery" and a non-CA fob has no battery door and has no 2032 battery in it. The combination is NOT in a non-CA fob!
So what is the truth about his car, CA or not CA car?!

It's kinda like telling me "I have a 4 cylinder 335i"...not possible!
Well sure it's possible, they could have a engine swapped 335i. Give people the benefit of the doubt.

OP, I'm questioning your knowledge based on this post ^ so you might be better off taking it to a dealership and let them solve it.
 

·
Registered
Joined
·
10 Posts
Discussion Starter · #7 ·
Thank you for all the feedback.

After further research, I believe the car has CA due to the following:

Parallel grove lines on the driver side handle
Removable 2032 battery in the FOB key

However, I tried the bells and whistles that comes with CA today and none of them work - i.e. car start without key in ignition hole, hand on door handle and grove line to unlock.
I also did a search of the VIN and CA is not listed as an option.

Kind of baffled. I may need to get the FOB key reprogrammed with the car? But this may be difficult to do here in Hong Kong. The car is EURO spec but was originally imported and sold in Japan (they added Japan specs to it - i.e. toll card reader in the rear view mirror). I then bought the car and was imported to Hong Kong. The car scene in Hong Kong is quite diverse and no one deals with dealers for used import cars and only indy garages.

Thank you for all responses and information!
 

·
Evil cider brewer
Joined
·
22,845 Posts
I never use the dash slot on my CA car. My thought was this was only used by the dealer to read codes during a service visit. Is my thinking on this correct?
It makes sense to me that putting a CA FOB in the dash might be killing the battery. If OP's car is CA, the best option might just be having a dealer figure out why CA is not working, as the issue could be FOB related, or a bad CA antennae.
 

·
Registered
Joined
·
3,384 Posts
Very puzzling, this specific combination:
  1. Parallel grove lines on the driver side handle
  2. Removable 2032 battery in the FOB key
  3. search of the VIN and CA is not listed as an option.
#1 and #2 in combination very much conflict with #3

If the car is NOT a CA car, it would usually lack the CA module which interrogates the CA key and tells the CAS it should open the door or start the car ("Auto Go").
 

·
Registered
Joined
·
3,384 Posts
Well sure it's possible, they could have a engine swapped 335i. Give people the benefit of the doubt.
A car badged with '335i' and having a 4 cylinder is NOT a '335i'...it is a 3 Series chassis with a 4 cylinder engine in it. Would YOU want to take that car to a drag strip to compete against "other 335i" or complete against other 2L 4 cylinder cars?!

I see some cars with the M-badge on the back (applied by the owner),

https://www.ecstuning.com/b-genuine...32332226479/?gclid=CIKM3qyimc8CFQeTfgodPgEPiQ

and wearing the badge does not make it a car built to M spec, either.
 
1 - 10 of 10 Posts
Top