I admit I was dumb enough to follow the aux battery delete trend on YouTube. But after reading Eddie's post about the aux battery protecting the computer, I quickly plugged everything back together.
What I learn when you unplug the aux battery, there are no warning lights because it disables them. Right after I put my aux battery back, I got a fuel cap warning and slow emissions leak check engine light. I've been driving almost 300 miles with the fuel cap off without any warning lights. I don't think it's coincidence.