Before going any further, get a jump off of something fairly robust. While B1318 is pointing to a low battery, they are stupidly sensitive to just a low reading that most other vehicles would ignore and start.
It's easy to think of a faulty battery as just exactly that, but you must remember that your car has several electronic control modules. They do not understand the term 'faulty' as you do. The control modules are computers that cannot think or apply common sense. If a battery is faulty there will be something faulty about it, and that could be one of many things. To us they're all the same thing. The battery's faulty and that's that, but to a computer it's a totally different matter. Different faults will cause different problems. Have your battery properly and comprehensively checked, or renew it anyway.
