how to tell when key battery low

Hello, If I'm not mistaken, you will get a message on the instrumentation telling you if it senses a low battery. However, it's cheap insurance to just replace them anyway: they are inexpensive. If your doors will not unlock automatically at times, it is often due to interference with the key -- something is preventing the radio frequency (RF) signal from transmitting automatically. This happens to me all the time -- if I have my key near my phone or other metal or RF blocking item in my pocket, it will prevent the door from unlocking. This could be happening to you too.