996 Porsche Alarm Triggers Out of Nowhere, Battery Fix Needed?

Hey there! I had a similar issue with my '09 Porsche Cayman last year. The alarm would go off out of nowhere in the middle of the night and sometimes wouldn't respond to the key fob at all. Turned out it was indeed the backup battery, plus some corrosion on the battery connections. Got it fixed at my local Porsche specialist, and they found the original backup battery was completely dead. They had to replace it along with cleaning the terminals. It wasn't a major repair, but it's something you want to address soon because a failing alarm system can drain your main battery too. The whole job took about an hour, and it's been working perfectly since then. Just make sure whoever does the work uses the correct battery spec for the alarm system, that's pretty important for these cars. Hope this helps! Let us know how it turns out.

Hey, thanks for sharing your experience! That sounds exactly like what I'm dealing with. Would you mind telling me how much you ended up paying for the fix? Also, just curious, have you had any other alarm-related issues pop up since the repair? Really appreciate the help!

Hey again! Just wanted to follow up on your questions. After seeing the mechanic, the issue turned out to be exactly what I suspected, a faulty backup battery in the anti-theft system. The total bill came to 330€, which included the new battery and labor. It was totally worth it though! Since getting it fixed, my Cayman has been running like a dream, no more unusual alarms going off in the middle of the night (my neighbors are pretty happy about that too!). Haven't had a single alarm-related problem since then. It's been about a year now, and the system works perfectly, the key fob responds immediately, and the alarm arms and disarms just like it should. The mechanic mentioned that these backup batteries typically need replacement every 5-7 years due to aging, so it's kind of a normal maintenance thing. Honestly, I wish I'd done it sooner, it would have saved me some headaches and probably some dirty looks from the neighbors! Let me know if you need any other info or have more questions. Good luck with getting yours sorted!

Thanks so much for all the details! I actually just got back from the mechanic today. You were spot on about everything! I found a reputable Porsche specialist across town who diagnosed and fixed it right away. The backup battery was completely dead, just like in your case. Total bill came to 295€, a bit less than what you paid, which was nice. The mechanic was super professional and even showed me the old battery. The whole process took about 45 minutes, and wow, what a difference! The alarm system is working perfectly now. No more unusual alarms, and the key fob response is instant. My neighbors will definitely sleep better now! Really appreciate you sharing your experience, it gave me the confidence to get this sorted quickly instead of putting it off. The mechanic also mentioned the 5-7 year replacement timeline, so I've made a note to keep track of that. Thanks again for all your help! Case closed on this one!