Skoda Octavia Car Alarm Problems

Sounds like a similar problem I had with my Octavia. The auxiliary battery is likely the culprit, especially if it's the original. Have you tried a system diagnosis to confirm the 'battery alarm' error?

Yes, the error is stored in the error memory - 'Battery Alarm System defective'. The car alarm isn't working. Is that what you experienced? Was it definitely the auxiliary battery, and was it difficult to replace?

Yep, that's pretty much what happened to mine. 'Battery alarm' error, no alarm function. I didn't try replacing the auxiliary battery myself as I was worried about messing something up with the car alarm system. I took it to a workshop, and they confirmed it was discharged due to ageing. They replaced it, and the error disappeared.

I had the auxiliary battery replaced. It cost 330€. The 'battery alarm' error is gone, and everything seems to be working. Thanks for the help.