[campb292]

What year is this car?

 

[campb292]

OK, a 2016 with 2 batteries means it is the 2016 Malibu Limited which is a gen8 car. I'll move this discussion over there.

I think you want this: P305F Check Engine Code

There is a bulletin and some videos of interest. P305F is often the module inside the positive battery fuse block when not the batteries or connections.