VW T5.2: Key Fob Not Working? (Fix)

Hello,
For the past few months, my car key fob has been malfunctioning more and more. Sometimes, in the morning, I can unlock the car, but later in the day, it stops responding to the key fob. Sometimes it works again in the evening, or even not until the next day.
- It definitely isn't the key fob.
- The central locking system itself functions properly and can also be operated via the interior locking mechanism.
- The immobilizer is not causing any issues with the affected key.
- The red LED on the key lights up when a button is pressed.
- For the first few months, there were no errors, but for the past few weeks, the error message "1179 Key programming incorrect" has been appearing repeatedly.
- During a "dead" state, re-pairing the key seems to be possible only after the aforementioned error message appears.

"Does anyone have any ideas? I'm hoping it's a problem with the remote control itself. I've already bought a new remote, I just need to pair it. For testing the central locking system, it should actually work even without the WFS coding, right?"

Regardless of this issue, I recently encountered a problem with VW where their diagnostic tool was unable to access the system, not even to read the VIN, even though they hadn't experienced any problems two weeks prior.
I don't think the two topics are related, but I still wanted to mention it.

Thank you very much!

I once bought some batteries that were supposedly Varta, but they had a no-load voltage of just over 3.3V. So, they looked perfect on the surface. However, the remote control would sometimes only work on the second or third press. Eventually, it stopped working altogether (without any error messages or a "low battery" warning on the instrument cluster). The next battery from the same batch showed a "low battery" warning on the instrument cluster after only one week.
The third battery didn't work any better either.

I suspect I've purchased a counterfeit item. Or, it could be a manufacturing defect in the production batch.

However, the voltage always indicated a fully charged battery, even without any load.

Therefore, I wouldn't rule out the battery prematurely. Instead, I would first purchase a battery locally from a store with a good turnover (to avoid getting a battery that has been sitting on the shelf for a long time). Nowadays, you can even find them at stores like Aldi.

I've tried several batteries from different manufacturers - the problem occurred with all of them. Also, the key eventually starts working again. Sometimes on the same day, but sometimes not until after three days...

I suspect now that there's probably a defect in the electronics of the key: I had a new key programmed the day before yesterday, and it's working perfectly so far, while the "problem key" is currently acting up again. I can't even reprogram it.
I'll continue to monitor it for a while, and if the new key doesn't show any issues, I'll assume that the old one is simply defective (and thankfully not the control unit or anything like that).