Audi Key System Failure: Battery or Deeper Issue Alert

I had a similar problem with my 2016 Audi A4 last winter. With some experience working on basic car maintenance, I can share what worked for me. The key fob started acting weird first, with inconsistent door unlocking. Then the car displayed the key battery low warning. After a few days, the keyless entry stopped completely. The fix was straightforward, just needed a new battery for the key fob. The workshop checked the whole system to ensure there were no other issues with the car electronics. Total cost was 37 Euro including diagnostics and the new battery installation. Some tips from my experience: Dead key batteries can trigger various error codes, Workshop testing confirmed no other low voltage issues, New battery restored all key functions completely, Regular key fob battery checks prevent sudden failures Could you share: When did you first notice the warning messages? Does the physical key blade still work normally? Have you noticed any other electrical issues? Did you recently experience extreme temperatures? This info would help determine if your case is similar to mine or if there might be additional factors to consider.

Thanks for sharing your experience. My vehicle has 174740 KM with the last service done 2 months ago. The warning messages started appearing just this week. The physical key blade works fine for manual unlocking, but the electronic key functions have completely stopped. The key fob wont respond at all now, even when held very close to the door handle. Based on your feedback, I will try replacing the key battery first since its the most cost-effective solution. Good to know it solved a similar issue in your case without needing more extensive repairs. No other electrical problems noticed so far and weather has been normal. Will update the thread after checking the battery.

Thanks for the update. Since we have almost identical vehicles, I want to add some details based on what worked for me in this exact situation. When my key fob battery got that low, I also experienced the complete loss of electronic functions, even when holding it right against the door handle. The total lack of response matches your symptoms perfectly. A few key points about my battery replacement experience: Used CR2032 battery type for the fob battery, Key battery cost was around 5 Euro, No reprogramming was needed after battery replacement, Full functionality returned immediately One important detail I forgot to mention in my first reply, if you replace the key battery yourself, make sure to carefully note the battery orientation. Incorrect installation can trigger new error codes. My fob has a small + symbol showing the correct position. The fact that your manual key blade works normally and there are no other electrical issues strongly suggests this is just a key battery problem, exactly like my case was. Since your car is well maintained with recent service, other causes are less likely. Keep us posted after the battery replacement. The error codes should clear automatically once the new fob battery is working properly.

Based on your last reply, I can definitely take comfort in knowing this is likely just a key battery issue. The symptoms match exactly, complete loss of electronic functions even when the fob is right next to the door, while the physical key blade works fine for manual entry. I appreciate the specific details about the CR2032 battery and installation tips. Will make sure to check the orientation carefully when replacing the fob battery to avoid creating new problems. Good to know the electronic key should work right away without needing complex reprogramming. The total repair cost of 5 Euro for a new key battery sounds much better than what I was worried about paying for potential electronic system repairs. Since my car was just serviced and shows no other electrical issues, this simple fix makes the most sense as a first step. Will get the battery replaced tomorrow and update this thread with the results. Thanks for helping diagnose what seems to be a straightforward dead key battery problem rather than a more serious low voltage issue with the car itself.