I have a 2012 Mazda 3i sport. A couple months ago I was having issues with the AT light and shifting. I had the TCM replaced and didn’t have issues up until now. I was on 840 and suddenly the AT light came on and my car started shifting. I pulled over and turned the car off. Turned back on and the light was gone. Started driving and it did it again. I checked the tcm and fluid and it seemed fine. I had the battery reset and it hasn’t done anything since, about a week. I’m just scared to drive my car at this point.

 

If it happens again or continues to happen it could possibly be a faulty shift solenoid A i replaced mine when this happened at 160k miles and it worked fine. Then with my other mazda3 i replaced **** solenoid and it was the tcm. It was refurbished and programmed and worked fine