Ranger Battery Drain

That sounds frustrating. I had something similar with my Ranger, although the error codes were different. Before replacing the battery sensor, have you checked the alternator output? A failing alternator can mimic a dead battery because it isn't properly recharging it. Also, are there any aftermarket accessories installed? Sometimes a poorly installed radio or alarm system can cause parasitic battery drain, even when the vehicle is off.

Thanks for the suggestions. I hadn't considered the alternator. I will check its output. I do have a trailer brake controller installed. Could that cause a parasitic drain, and how would I check?

The trailer brake controller is worth investigating. Disconnecting it temporarily would be the easiest way to see if it's the source of the drain. However, given the error messages and symptoms, a faulty battery sensor is still possible. These sensors can fail intermittently. To avoid further troubleshooting, it might be best to take it to a workshop to check the error memory and the battery sensor.

I appreciate the input. I had the vehicle inspected at a workshop. The battery sensor was indeed defective. The total repair cost was 315€.