I have a 2013 Mazda CX9 with a key-less entry fob that allows me to unlock the doors and start the car. The fob works perfectly most of the time. I can lock and unlock the doors both with the buttons on the key fob itself and by pressing the buttons on the door so that I don't have to use the fob. It also allows me to open and unlock the tailgate and start the car. The problem is that all of sudden the car will stop detecting the fob and a red key light will start blinking on the dash and making a beeping sound. Usually the issue goes away after a few minutes. Every now and then it won't detect I have entered the car and I'll have to pull the physical key out of the fob to start the car. My first thought was obviously the battery so I replaced the battery, no change. So then I decided to use the second fob which I had actually never used since I had purchased the car , thinking the first fob had an issue. Of course after 6+ years the battery was dead in the second fob but after I replaced the battery it worked but experienced the exact same symptoms as the first fob, randomly not being detected by the vehicle but only the inside not outside for unlocking the car. This leads me to believe that the fob is not the issue. Is there some sort of interior detector that I should be checking or replacing? Ive search and cant find anything online. Thanks for any suggestions.

 

I would recommend going to Mazda for inspection, Even if they can't fault it, they can save data logs and send them to Mazda head office for in depth analysation.