I purchased a used 2015 mazda6 in 2020. last year I noticed the bsm system blinking. the 1st time I had to even look up what it meant. after that point, I started noticing on days it was very cold (usually around 30 degrees or lower) the system would be a dice roll on if it would work. usually after it warms up (weather or driving long enough) the system seems to come back online. to the best of my knowledge, the car has never been in an accident. of course this is not to say it's never been hit without my knowledge in a parking lot. I'd rather not go to a dealership to listen to all the upsales of what my car needs so I'm looking for some information where I should guide my mechanic to look. I've seen some references on checking the wiring, sensors being located in the rear bumper but is there anything else that may be the root cause?