Highlander battery draining

I understand your frustration with the battery issue. I have a Toyota Highlander as well, and I had similar symptoms not too long ago. Have you checked the battery terminals for corrosion or loose connections? Also, how old is your current battery? A failing battery can sometimes cause similar symptoms, even if the sensor is faulty.

Thanks for the quick reply! I did check the terminals, and they seem clean and tight. The battery is about three years old, so it's not brand new, but I wouldn't expect it to be completely dead yet. When you had this issue, did the error code specifically point to the battery sensor, or was it something more general like a low voltage code?

Ah, three years is getting up there for a battery, even though it shouldn't be totally gone. In my case, the error code was vague, but the dealership diagnosed it as a faulty battery sensor after a thorough check. Given your symptoms and research, it does sound like the sensor. I'd recommend getting it checked out by a trusted mechanic to confirm before replacing parts. Could save you some money and headache!

Thanks a lot for the advice! I appreciate you sharing your experience. I took it to my mechanic, and after testing, it was indeed the battery sensor that was defective, causing the parasitic draw. The repair, including the sensor and labor, came out to 315€. All sorted now!