The Jetta's key fob had a mind of its own this weekend. The thing did just fine when it came to opening the car, but it wasn't quite pulling off the job of locking the Jetta's doors securely when I was ready to exit the red four-door and go on my way. Click, click, click. I'd press the thing over and over again and still it wouldn't do as it was told.
I figured the key fob battery couldn't be the issue, since the red light on the fob lit up when it was activated; also, when I locked the doors (while seated within the car, using the interior door locks), the key fob opened the locks without a hitch.
After poring through the owner's manual for a moment or two, I learned the source of the problem: The car's key needed to be synchronized. Read all the thrilling details involved in this process after the jump.
The first step involved whipping out the fob's key bit, which I then used to pry open the cap on the front driver-side door handle. Doing so left the handle looking a bit exposed, as shown in the photo below.
Next, I pressed the "Unlock" button on the key fob, and quickly followed that up by inserting the bit into the door lock (the manual says insertion needs to take place within a minute of pressing the "Unlock" button). Then I entered the car and started the ignition.
After following those steps, the fob was back in sync with the car, and I was able to use it to lock the doors. And what caused this lack of synchronization to befall the Jetta in the first place? The manual says the fob and the car may become out of sync when the fob's "Unlock" button is repeatedly pressed while outside operating range.
Have you ever had to synchronize your car's key fob? Was the process as simple as it is with the Jetta?
Warren Clarke, Automotive Content Editor @ 17,162 miles
esoterica says:
03:38 PM, 02/13/12
"Have you ever had to synchronize your car's key fob?"
Never. VAG mis-engineering strikes again.
jdubbs19 says:
08:51 PM, 02/13/12
Really? Reprogramming the key?
I haven't had the need to do it in four years, a little surprising the MkVI series needs that. A little disappointed that it needs to be reprogrammed so soon.
church123 says:
09:01 PM, 02/13/12
I have a similar problem in my MY00 S2000. Sometimes the car will lock but not unlock if I've been away for awhile (I'm assuming that the buttons are getting pressed in my pocket). I can keep pressing the lock button and you can hear the solenoids operating, but the unlock button does nothing. I can usually get it to work by pressing the lock button 3 times in a row and then pressing the unlock button. I'm assuming that some sort of rolling code is used for the unlock signal and you have to resync.
fusion84 says:
04:16 AM, 02/14/12
This has got nothing to do with "VAG-misengineering" or sth. like that. Desynchronizing happens with basically all modern car remote keys if you press the buttons often enough while out of range.
The key communicates the car by sending a code-number, which is created by a number generator. Both the car and the key share the same type of (not quite-random) number generator. After any command that is sent to the car by the key, it will generate the next number and save it. Just like that, the car generator will make up a new number (since it is the same generator as in the key, it will be identical) every time it receives a new number.
If you sent commands while out of range, the key will sent out codes and continue making up new ones, however the car won't. The key and car will get out of sync. To avoid that happening after just a few clicks, the car usually is ok with accepting any of a number of codes that would follow after the current one. However, if you press too often, they will get out of sync and you have to manually reset them.
The fact that opening still works kind of points to VW using different codes for Opening/Locking, so only that function was out of sync...
robert4380 says:
07:51 AM, 02/14/12
I'm surprised they even told you in the owners manual how to fix that. I would have guessed they'd want you to bring the car in for service at $130/hr to re-sync it.
esoterica says:
10:22 AM, 02/14/12
"Desynchronizing happens with basically all modern car remote keys if you press the buttons often enough while out of range."
No, it doesn't. Just because VAG's engineering works this way does not mean that all vehicles do.
fusion84 says:
01:53 AM, 02/15/12
Basically this might be true - but this is the way just about all remote-keys work. If you google a bit, you can find people resynching key fobs from every manufacturer.
In fact, here are synching-guides for basically any manufacturer: http://www.programyourkeys.com/Program_Keys.html
esoterica says:
08:41 AM, 02/15/12
Of course a car has to be able to be programmed to new keys, otherwise you'd have to replace the car if you lost your keys.