# Changing the Key Fob Battery



## mark_d_drake (Aug 17, 2006)

OK, so I guess I discovered the hard way that one disadvantage of the roof module is that holding the buttons down to raise and lower the roof drains the battery much faster than 'normal' operation would. Since this appears to be a direct result of using the roof module I didn't really think I could ask VW to replace the battery under warranty







..
So in case any one's interested here's how to replace the battery.. With thanks to Brendan at Boardwalk...

Step 1: Open the Keyfob by inserting an object into the key ring holder and pulling the top and bottom apart








Step 2: Seperate the two halfs.








Step 3: Open the top half to expose the battery








Step 4: Carefully remove the battery.. Its a CR 2032. Note it goes in positive side down..








Step 5: Insert new Battery. I used a Duracell Lithium replacement
















Step 6 : Close the cover and push top and bottom back together..


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## just4fun (Oct 29, 2006)

*Re: Changing the Key Fob Battery (mark_d_drake)*

Well, I gotta admit I'd never have figured that out on my own.
Thanks for the info Mark
Kevin


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## just-jean (Sep 14, 2006)

*Re: Changing the Key Fob Battery (just4fun)*

http://****************.com/smile/emthup.gif http://****************.com/smile/emthup.gif


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## Small5 (Jan 19, 2007)

this doesn't reset the code in the fob and require it to be "re-synced" with the car?
either way, good write up


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## mark_d_drake (Aug 17, 2006)

*Re: (Small5)*

Nope, worked just fine, locked, unlocked poped the trunk and opened and closed the roof.


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## Small5 (Jan 19, 2007)

*Re: (mark_d_drake)*


_Quote, originally posted by *mark_d_drake* »_Nope, worked just fine, locked, unlocked poped the trunk and opened and closed the roof.

hmm interesting. so i guess the other way around (if your car battery dies), that's when the lose their sync.


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## [email protected] (Feb 14, 2005)

*Re: (Small5)*


_Quote, originally posted by *Small5* »_this doesn't reset the code in the fob and require it to be "re-synced" with the car?
either way, good write up









If you get the old battery out and the new one in within a reasonable period of time, you won't lose the code. If you leave it apart for 10 min or so, I've seen them not synch up again. 
Nice pics Mark! http://****************.com/smile/emthup.gif They get easier to pull apart the older the get.


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## GTI Ace (Aug 14, 2005)

*Re: Changing the Key Fob Battery (mark_d_drake)*

Thanks for the good write-up. Its the simple pleasures (like a working fob) that make life good!


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## [email protected] (Feb 14, 2005)

*Re: Changing the Key Fob Battery (GTI Ace)*

Agreed. The Fob died in my BMW, and it is the only key I have for it. VW is smart and they use a battery. BMW uses a capacitor and the key charges through inductance, so once the capacitor dies, the key dies. Talk about taking a simple problem and making it complex...
Now I'm back to the 1980's way of opening up the car with the door lock till my new key shows up.


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## mattynovak (Dec 10, 2007)

*Re: Changing the Key Fob Battery (mark_d_drake)*

Kudos Mark. A most useful tip. Thanks! http://****************.com/smile/emthup.gif


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## solarflare (Mar 28, 2007)

*Re: Changing the Key Fob Battery ([email protected])*


_Quote, originally posted by *[email protected]* »_Agreed. The Fob died in my BMW, and it is the only key I have for it. VW is smart and they use a battery. BMW uses a capacitor and the key charges through inductance, so once the capacitor dies, the key dies. Talk about taking a simple problem and making it complex...
Now I'm back to the 1980's way of opening up the car with the door lock till my new key shows up.









Super caps, as they are known, are replaceable if you have soldering skills. If you can dissassemble the fob to get the capacitor information, (capacity and voltage) you can replace the cap for a lot less then I imagine BMW will charge you for a new fob. You can probably find the cap at an online parts house like http://www.mouser.com (they have no minimum order requirement), maybe even find the exact part. Here's a link to a page that lists some of these parts that they have. http://www.mouser.com/catalog/632/621.PDF
I had to replace one of these supercaps in a clockradio of mine. It was used to keep the time on power failure.


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## [email protected] (Feb 14, 2005)

*Re: Changing the Key Fob Battery (solarflare)*


_Quote, originally posted by *solarflare* »_Super caps, as they are known, are replaceable if you have soldering skills. If you can dissassemble the fob to get the capacitor information, (capacity and voltage) you can replace the cap for a lot less then I imagine BMW will charge you for a new fob. You can probably find the cap at an online parts house like http://www.mouser.com (they have no minimum order requirement), maybe even find the exact part. Here's a link to a page that lists some of these parts that they have. http://www.mouser.com/catalog/632/621.PDF
I had to replace one of these supercaps in a clockradio of mine. It was used to keep the time on power failure.

You are a wonderful person. I've been soldering since I was a kid (model trains helped me out a lot), and this way looks like it can save me a lot of money. Thank you so much for the information. http://****************.com/smile/emthup.gif 
I love giving car buying tips and information to this site, and I'm glad a little gem like this came up so I can reap benefit of information too.


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## solarflare (Mar 28, 2007)

*Re: Changing the Key Fob Battery ([email protected])*

You're very welcome http://****************.com/smile/emthup.gif Let me know if I can help any further. BTW, since you have limited space in a key fob you may want to verify the dimensions of the new capacitor as well as capacity and voltage. Not every capacitor manufacturer has the same dimensions for the same capacity and voltage part.


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## JFNovae (Nov 2, 2004)

*Re: Changing the Key Fob Battery (mark_d_drake)*

great write up! how do you open and close the roof?! knowing i can change the battery id def use this. Thx J


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## mark_d_drake (Aug 17, 2006)

*Re: Changing the Key Fob Battery (JFNovae)*

3rd Party roof module from 
https://www.wilhelmy-it.de/sms...g.pdf


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## cjboffoli (Sep 22, 2007)

*Re: Changing the Key Fob Battery (mark_d_drake)*

Please don't just toss these "button" batteries in the trash. There are a number of places (including Home Depot and IKEA locations) that have battery recycling bins. They'll take them and will recycle or dispose of them properly.


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## callmeal (Sep 8, 2006)

*Re: Changing the Key Fob Battery (mark_d_drake)*

Mark,

Maybe it's me but in step 3, how does the top of the fob separate from the bottom? Slide it off (which way to rear or to the front) or pop off by prying?
I don't want to break it!









Thanks 
Allen


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## callmeal (Sep 8, 2006)

*Re: Changing the Key Fob Battery (callmeal)*

OK I answered my own question, I had to pry the top (no buttons) straight up from the bottom


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## blue4max (Feb 17, 2008)

*Changing the Key Fob Battery (callmeal)*

Is this common to have to change the Fob battery? I just traded in a '95 and the original battery in that Fob was still kicking.


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## mark_d_drake (Aug 17, 2006)

In my case I put it down to use a After market roof module which allows the roof to be operated from the remote. To open or close the roof you have to hold the key down for 5 seconds, much longer than required to lock or unlock the door. This is why I felt it was appropriate to replace the battery myself


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## callmeal (Sep 8, 2006)

*Re: (mark_d_drake)*

Mark,
I'm usually the driver of the car, my wives remote still works perfectly (low use). My remote would lock the car, but would not unlock it. The small red signal indicator would not light. The car is just over a year old (Dec 16th)
Allen


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## blue4max (Feb 17, 2008)

*Remote top control*

Where did you get the parts necessary to remotely operate the top?


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## mark_d_drake (Aug 17, 2006)

*Re: Remote top control (blue4max)*


_Quote, originally posted by *blue4max* »_Where did you get the parts necessary to remotely operate the top?

See the earlier posts in this thread for full details.


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## [email protected] (Feb 14, 2005)

*Re: (callmeal)*


_Quote, originally posted by *callmeal* »_Mark,
I'm usually the driver of the car, my wives remote still works perfectly (low use). My remote would lock the car, but would not unlock it. The small red signal indicator would not light. The car is just over a year old (Dec 16th)
Allen

Allen,
If it will lock but not unlock, it sounds like your remote might have a dead button. I doubt it is software since it wouldn't have worked from day one, and a salesmen would have caught it (well, we can hope...







)
If the button died, it should be covered under warranty. Just remember to bring in all of the keys so they can all be programmed.


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## callmeal (Sep 8, 2006)

*Re: ([email protected])*

Brendan,
If that was the case then changing the fob battery, wouldn't have fixed the problem. Perhaps my prying the case apart fixed a stuck button, either way it works now (with a brighter indicator light).

Allen
_Modified by callmeal at 10:56 AM 2-20-2008_


_Modified by callmeal at 10:56 AM 2-20-2008_


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## [email protected] (Feb 14, 2005)

*Re: (callmeal)*


_Quote, originally posted by *callmeal* »_Brendan,
If that was the case then changing the fob battery, wouldn't have fixed the problem. Perhaps my prying the case apart fixed a stuck button, either way it works now (with a brighter indicator light).

Allen


Allen,
On the bright side, it's good to hear the key is working without needing a trip to the dealership.


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## theothereos (Oct 9, 2006)

*Re: (callmeal)*

I have the exact same issue - Car is going in for oil change next week and this is one of "other issues" I want them to resolve. 
-dawn

2/27/08 - Update: Dealership replaced battery for free and seems to have resolved issue. Weird that would lock, unlock the trunk, but not unlock the doors.







Can't beat the price and it wasn't a special trip in for me so no complaints. 


_Modified by theothereos at 3:53 PM 2-27-2008_


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## IHateTheSoundOfSirens (Feb 25, 2006)

I want to thank you for the step by step and photos... I had to replace my battery and this was perfect. Cheers!


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## nigelmercier (Jul 8, 2012)

Small5 said:


> this doesn't reset the code in the fob and require it to be "re-synced" with the car?
> either way, good write up


I've just gone through this procedure to change the battery, many thanks. However, the remote still won't work, although the LED flashes. Can I re-sync it myself?


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