Audi RS4 Key Fob Failure, Dead Battery vs System Issue

Had similar issues with my 2011 Audi S4. The key fob battery warning is usually straightforward but can be misleading. When my auto key stopped working, I initially thought it was just a low voltage issue with the fob battery. After replacing the fob battery myself, the warning persisted. The problem turned out to be related to both the key battery and corroded contacts inside the key housing. The mechanic needed to clean the contacts and reprogram the key to sync properly with the car. A few symptoms that indicated it wasnt just a simple battery replacement: Warning stayed on after new battery, Key worked inconsistently even with fresh battery, Car sometimes failed to recognize the key completely This was not a serious issue but required proper diagnosis. The key fob needed partial disassembly to fix the contacts. If you get a new battery and the problem continues, its likely the contacts need attention or the key needs reprogramming. Worth checking both battery terminals in the car key before heading to a shop, as low voltage from a weak battery can sometimes mimic more complex issues.

Thanks for sharing your experience. I had almost identical symptoms with my RS4 electronic key last winter. Changed the fob battery first but kept getting warnings. Turned out there was corrosion on one contact that needed cleaning. Did the repair costs stay reasonable in your case? Also wondering if youve had any recurring issues since getting it fixed? My key has been working perfectly after the repair but always good to know what to watch out for.

After the mechanic fixed the issue, my S4 key fob has worked flawlessly. The total cost was 37 Euro for the battery replacement, contact cleaning, and reprogramming, quite reasonable considering the specialized work involved. The key battery low warning disappeared completely after the repair. Its been over a year now with zero recurring problems. The key consistently works for both locking and keyless entry. If you maintain your auto key properly and avoid exposing it to moisture, the contacts should stay clean and functional. A good tip is to periodically check the fob battery voltage before it gets too low. This helps prevent strain on the contacts and ensures reliable operation. When a battery replacement is needed, using high-quality batteries can also make a difference in longevity. Your experience matches what many Audi owners discover, while a simple battery swap sometimes fixes key issues, proper contact cleaning and programming often provides the complete solution.

Just went to get my RS4 key fixed last week. The mechanic found exactly what you described, corroded contacts plus a dying fob battery. Total bill came to 45 Euro which seemed fair for the work done. The repair process was quick. They cleaned the contacts, installed a fresh key battery, and reprogrammed the electronic key in about an hour. No issues since then, the keyless entry works perfectly now and the dashboard warning is gone. Much better experience than my previous shop visits. Good to know this is a common issue with a straightforward fix. Will definitely keep an eye on the contacts and replace the battery before it gets too weak next time.