The remote key works erratically - sometimes the remote operates all but one of the locks, and other times it is only one or two. Occasionally it does not operate any any at all. I changed the battery for the first time about one year ago, but have not tried a new one since. I thought that it might be something else.
Which battery? The car battery or the remote battery? It could be, but I doubt if it is, the car battery. I also doubt if it is the remote battery since the remote does not work each lock independently. I would suspect wiring.
I’ve seen this before in my friend’s '99 passat.
In his case, it turned out to be a bad electrical connection inside the driver’s door.
Cleaned the contacts and all was well.
You might want to have a VW dealer (or specialized VW shop) scan the central convenience computer for error codes. It will likely show some faults that will allow them to track down the problem.
The remote battery. I figured that it was not likely the cause but could not understand why it worked sometimes and not others. Wiring seems like a likely cause.