Fix Your Dead Audi Key Fob with Simple Battery Swap

Having dealt with a similar electronic key issue on my 2003 Audi A3, I can share my experience. When my key fob stopped working, I also got the low voltage warning. The dead key symptoms were exactly like yours, no remote locking or unlocking. Since I do basic maintenance myself, I first considered a DIY battery replacement, but wasnt confident about opening the key without damaging it. Took it to a workshop where they confirmed it was just a key battery issue. The fix was straightforward, they replaced the battery and reprogrammed the key to sync with the car. Total cost was 37 Euro, including parts and labor. Been working perfectly since then. Quick heads up, while battery replacement often solves this, knowing your exact model and key type would help determine if theres anything else to consider. Could you share: Whether this is the original key, If the physical key part still works for manual locking, If you see any other warning messages on the dashboard This way we can rule out more complex electronic key issues that sometimes occur in these models.

Thanks for the feedback. My A2 has 192263 KM km on the clock, with the last service done 2 months ago. The physical key still works fine for manual door locking, and there are no other dashboard warnings. This is actually the original electronic key from 2005, have never had issues with it before this low voltage warning started appearing.

Based on what you shared, especially about it being the original key from 2005, this is almost certainly just a battery issue. Had the exact same situation with my A3, original key that worked flawlessly for years until the low voltage warning appeared. The fob battery in these electronic keys typically lasts 4-5 years, so getting nearly 18 years from the original is impressive. Since your physical key works and theres no other error messages, its extremely unlikely to be a more complex electronic key system problem. Quick tip from my experience: after the battery replacement, you might need to use the key a few extra times for the auto key system to fully resync. This is normal behavior for these models when installing a fresh battery. Cost should be similar to what I paid, around 35-40 Euro total if you go to a workshop. The battery itself is fairly cheap (under 10 Euro), but having a professional handle the replacement eliminates risks of damaging the key housing during disassembly.

Thanks everyone for the detailed responses. After reading about your experiences, I feel much more confident about this just being a battery issue. Since my physical key still works and its the original fob from 2005, getting 18 years from the first battery seems like a good run. Going to book it in for a battery replacement this week. The 35-40 Euro cost seems reasonable, and Id rather have a professional handle the electronic key work than risk damaging anything trying to do it myself. Good to know about the resyncing process too, will make sure to test the fob several times after the replacement. Will update here once its sorted in case anyone else runs into similar low voltage warnings with their auto key system.