XC60 auxiliary battery alarm fault

I had a similar issue with my XC60. The auxiliary battery can definitely cause those symptoms. Have you checked the battery's voltage? A weak auxiliary battery often triggers alarm system errors. A battery check might confirm this.

Thank you for your quick reply. I haven't checked the voltage yet, but I'll do that. Where is the auxiliary battery located, and what voltage should I expect?

The auxiliary battery is usually under the floor in the trunk. As for the voltage, a healthy battery should read around 12.6 volts when fully charged. If it's significantly lower, say below 12 volts, that’s a strong indicator it needs replacing. However, since it's related to the alarm system, I'd advise having a workshop take a look, just to be certain.

I appreciate the advice. I had the auxiliary battery checked, and it was indeed discharged. Replacing it for 330€ solved the problem. Thanks again!