I have a 2016 Mazda 6 that up until recently had no issues. I have about 40k miles and recently I was experiencing my battery being dead randomly. I had it checked and auto parts store confirmed a cell was faulty. I bought and replaced battery and once I started the car my check engine light came on.i went to read the code and now my OBD2 module is out. The car runs fine, starts fine now and even though I am confident switching batteries is somehow at fault and my car's engine is fine, I can't figure out what to do to svd the issue. Please help!