i have an 04 mazda 6 2.3l when motor is cold start it starts up no problem then I start driving as I get up to speed the car will all of a sudden die and you will see the anti theft key light turn on the car jerks then it will either completely die or turn back on and keep going also it will sometimes have the battery light also come on when the key light comes on it has been doing this for a while now and I really want to fix this problem for my wife. I think it might be that battery because when I took the car into the shop they left the lights on and killed the battery when I went to go pick it up they charged the battery and its been good so far but the battery is two years old now! time to replace but I want to find the problem of why the car dies in mid drive and the anti theft key light comes on. its so weird but once the car is warm from driving it doesn't continue only when its cold and you start driving also I have engine code of p0302 witch is cylinder 2 misfire i've replaced the plugs and wires I think It has to be connectivity to the plug but will this have anything related to the car turning off in mid drive with the anti theft light on will it have to do anything with the key? I was thinking about getting a new battery and key to see if that fixes the problem also has anyone experience any symptoms I desperately need help because I do not want to take to shop again but I might have to if I cant find and fix the issue. im thinking battery but car fires right up no issue battery is still good when I had tested the only other thing I can think of is the key might have an issue I know my daughter likes to put the keys in her mouth but its been awhile since ive seen that happen idk if it could be poor signal from key or what any advice would be helpful and I am grateful for you guys thank you god bless!

 

It sounds a bit like your alternator is going out. The battery light will only come on if the alternator is under/over charging. I would attack that problem first. Check all connections and test the alt output with and without headlights/wipers/ac on and with no load.