Audi RS5 Alarm Dead: Aux Battery Failure Warning

Had a similar situation with my RS7 (2017) last winter. The alarm system shutdown was indeed caused by a failing auxiliary battery. This separate battery powers the alarm system and some other electronic functions even when the main car battery is disconnected. The auxiliary battery tends to fail gradually, causing the alarm system to malfunction first before complete failure. The battery signal warnings started appearing on the dash intermittently before the full system shutdown. When the auxiliary battery problem became severe, the central locking also started acting erratically. The repair itself was straightforward but required specific diagnostic equipment to properly reset the alarm system after replacing the auxiliary battery. It was a serious issue that needed immediate attention since a failed auxiliary battery can drain the main car battery and leave you stranded. What you describe matches the typical symptoms. The specific error code and complete alarm system failure are classic signs of auxiliary battery problems in these models. Getting it fixed by a qualified shop is important since improper installation can cause issues with other electronic systems.

Thanks for sharing your experience. Your symptoms sound exactly like what I went through with my RS5. The system diagnosis confirmed a faulty auxiliary battery and I got it fixed right away. Really curious about the repair cost you paid, would you mind sharing? Also wondering if youve had any other alarm system issues since the battery replacement was done. Its been about 8 months since my repair and everything is working perfectly with the alarm system, but always good to know what to watch out for.

The auxiliary battery replacement in my RS7 cost 330 Euro including the electrical system diagnosis and installation. The investment was worth it since the car alarm and all related systems have been working flawlessly since the repair. The battery check showed the old unit was completely drained due to ageing, which explained all the electrical issues we were experiencing. Looking back, fixing it promptly was the right call, it prevented potential damage to other electronic components. After the repair, I havent seen any more warning messages about the alarm system being defective. Its reassuring to hear youve also had no issues for 8 months after your repair. These auxiliary batteries typically last several years when properly maintained, so we should both be good for a while. Just keep an eye on your dashboard for any early warning signs of electrical issues, but with a new auxiliary battery, the alarm system should remain stable and reliable.

Thanks for the advice. I went ahead and got it fixed at the mechanic last week. The system diagnosis confirmed it was the auxiliary battery causing all the electrical issues. Total repair came to 295 Euro which included the new battery and labor. Process was quick, dropped it off in the morning and picked it up same afternoon. Tech showed me the old battery which was completely dead. The alarm system works perfectly now and all those annoying battery signal warnings are gone. What a relief to have this sorted. The electrical issue was really starting to worry me, especially after that one morning when the alarm went off out of nowhere at 5am. Good to know these auxiliary batteries just need replacing every few years, will definitely keep an eye on any early warning signs going forward.