Hello guys, soo ive been constanly having battery issues with my car for the last year. Soo now whenever i stop driving the car for a while I disconnect the negative terminal to stop the battery from draining. Now my check engine light is on. And i read my codes and it is a P1515 code. I also read my codes on the bmw scanner and im getting a bunch of random stuff that doesnt seem important. So i looked up P1515 solutions and im getting alot of mixed reviews/answers.