Audi RS3 Key Fob Problems: Quick Battery Fix Guide

As someone with some experience working on Audi electronics, I had a similar issue with my 2020 S3. The key fob started acting up and the low battery warning appeared on the dashboard display. The electronic key gradually lost its effectiveness, first the keyless entry stopped working, then the remote locking became inconsistent. The low voltage warning was definitely the first sign something was wrong. I took it to a workshop where they diagnosed the key battery was nearly depleted. They replaced it with a new one, ran some basic tests to ensure proper communication between the key fob and the car, and everything worked perfectly again. The whole service cost 37 Euro and took about 30 minutes. To help further with your specific case, could you share: How old is your current key battery? Are you using the physical key as backup? Does the issue persist with a second key if you have one? Did you notice any other electrical issues before this started?

Thanks for sharing your experience. Since my last service at 65000km the car has done another 3132km. I tried using my spare key and noticed the same behavior with both key fobs. The batteries are original from when I got the car new, so about 18 months old now. Based on your feedback, a battery replacement might be the straightforward fix I need. Good to know it was a quick and relatively inexpensive repair. The physical key works fine when manually unlocking, but the electronic functions like keyless entry and remote locking have completely stopped working on both fobs. No other electrical issues noticed so far. The low battery warning showed up consistently for about 3 days before the fobs stopped working entirely. Would you recommend going ahead with just a key fob battery replacement first before looking into other potential issues?

Thanks for those details. Based on my S3 experience and your symptoms being nearly identical to what I faced, I strongly recommend starting with a battery replacement for both fobs. The 18-month lifespan of your original batteries aligns with typical electronic key battery durability, especially with frequent use. The fact that both fobs are showing the same behavior and the physical key still works perfectly confirms my suspicion that its a simple low voltage issue rather than a more complex electronic problem. The gradual failure pattern, starting with the low battery warning, followed by complete loss of keyless functions, matches exactly what happened with my fobs. A fob battery replacement should resolve this completely. Just ensure the battery installation is done correctly, as improper seating can sometimes cause connectivity issues. After my battery replacement, I needed to lock and unlock the car a few times to resync the fobs, which is completely normal. If the issues persist after replacing both batteries, then it might warrant checking the cars antenna system or key recognition module, but based on what youve described, thats unlikely to be necessary.

Thanks for the detailed response. After hearing about your similar experience, I feel more confident about getting just the battery replacement done first. Its reassuring that my key fob symptoms match what you encountered, especially the warning sequence and complete failure pattern. I will get both key batteries replaced and try the resyncing process you mentioned. Having the physical key still working is also a good sign that its likely just a low voltage issue rather than something more serious with the cars electronics. I will schedule the battery replacement service this week. The 37 Euro cost seems reasonable, and a 30-minute fix would be ideal. If anything unexpected comes up after the auto key battery replacement, I will update here about whether it solved the keyless entry problems completely. Good to know about the potential need to resync the fobs after, I will make sure to test both keys thoroughly once the new batteries are installed.