XC90 Hybrid Battery Issue

I had almost the exact same symptoms on my XC90. A discharged battery can be caused by so many things in modern vehicles! The error message, weak/flickering lights, and trouble starting are classic signs. The error codes will give you a head start, but did you check the quiescent current? That's the current drawn when the car is 'sleeping'. A faulty module can keep the system awake, drawing excessive current and draining the battery. Was the battery replaced recently and do you know the type of battery which was mounted? Did you register the new battery with your diagnostic device?

That's a great point about the quiescent current, something I hadn't considered. I don't have the equipment to measure this but I will try to get my hands on it. The battery is original, so it's never been replaced or registered. So, if it wasn't the quiescent current nor an unconfigured/unregistered battery, could a defective battery sensor really cause all these symptoms, including the error codes and starting issues? If the sensor is delivering the wrong value, the system might interpret this as a discharged battery. If so, do you know how I could locate the sensor cable?

Yes, a defective battery sensor definitely could be the culprit. While it's designed simply to measure voltage, it can also affect the charging process if it provides faulty data. The car's computer relies on these readings to regulate the charging. A faulty reading might stop the charging or causes incorrect charging parameters. I would not test the sensor cable, since it could cause more damages and I would really recommend visiting a workshop. With the right diagnostic tools, they can easily check all modules and the sensors voltage. A defective sensor will very likely be your issue.

Thank you. You were totally right! I took it to the shop, and the diagnostics pointed straight to the battery sensor. They replaced it, cleared the error codes, and everything's back to normal. It cost me about 315€, but that's a small price to pay for peace of mind. I really appreciate your help!