Ok so here'* the deal the last couple of days my car has been missing. I think it'* a spark plug wire that keeps popping off. Well today I decided to pull codes and came up with a 31. What exactly is it? The car is running fine now and I snapped my plug wire back on.

Park/Neutral safety switch. It means you can shift out of park without your brake being applied (because the switch is faulty/misadjusted). Most likely. Ignore it.