Have been following the battery recoding topics for a while and I think my experience is really worth sharing.
In short, YES, you need to recode the battery code.
Here is a full story why:
My car is a 05 D3 w12, with around 80000 miles. It is a one owner car belongs to my family. I got the car 3 years ago and ever since I got it, I noticed the door handle touch unlock function and power boot never works when the car locked over about 5 mins. Those function works within a very short time period after the car locked. And, an energy management warning will pop up if I only turn the ignition on. Also, the battry level shows it at minimum level all the time.
Despite all those problems, the car runs great even I parked the car over one month, it will start without any jiggle.
I checked the battry and there was a 9 years old in the trunck, so fitst instance, the weak battery is the problem source.
I really want the touch unlock function to work, so I installed new battery, whitout change the coding of battery. After new battery installed, the battery level shows high and the touch unlock and power boot works as they should be.
However, I noticed the battery level is dropping slowly even after I drove the car for a long distance. Until some day, the car behaves excatly like the beginning state.
As all experienced car guys should, I suspect the alternator goes bad and not charging the battery, but I checked the battery voltage with a multimeter shows it was very healthy. Next I thought maybe there is a short in the system, drain the battery and caused the car went into battery save mode after I locked the car, makes very much sense. Then I checked and checked for a really long time, there was none.
Finally, half year passed by, one day I decide to gave the recoding a try. I hooked up VCDS and 2 mins later, all wired problems gone. End of story.