Titan Battery Draining

That sounds frustrating. I'm no expert, but I had a similar issue with my old pickup truck. Have you had the battery tested to rule out a dead cell? Also, is anything drawing power when the truck is off? A faulty relay or a glove box light can drain the battery. Could it be your alternator not charging properly? Have you considered checking it?

Thanks for the suggestions! I haven't had the battery tested professionally yet, but the voltage seemed a bit low even after charging when I checked it with a multimeter. I also looked for any obvious parasitic draw, but didn't find anything. Is there a reliable way to test the alternator myself without special equipment? Could a defective battery sensor cause all these issues?

If the voltage is low even after charging, the battery might be failing, or the alternator is faulty. Testing the alternator without equipment can be tricky. A defective battery sensor can definitely cause charging issues and lead to a discharged battery. It might be worth getting it checked, but with all those symptoms, I'd suggest taking it to a reputable workshop for a proper diagnosis. They'll have the right tools to pinpoint the problem quickly and accurately. Good luck!

Regarding my Nissan Titan's battery issue: I took your advice and brought it to a workshop. It turned out to be a defective battery sensor, just as you suspected! The sensor was causing the battery to discharge even when the engine was off. The total repair cost, including the sensor replacement and labor, was 315€. Thanks again for your help!