About a week ago I started getting this problem. My key works when pointed directly at one of the infra red sensors on the door handles, but it's like the FM signal isn't getting through somehow. Also, after the car has set all night, sometimes even the IR sensors won't pick up, but the little light on the key still flashes when I push a button. For that matter, I replaced both of the 2025 batteries in the key itself. I have to pull out the mechanical key, unlock the door, open it, and when all hell breaks loose, stick the electronic key in the ignition to shut it up! Funny thing is, when I've driven the car a few miles, not even enough to warm it up, at least the IR sensors work again, if not the FM.
I had the car in recently and was told by the mechanic that I'm getting low voltage signals all over the car and that the car's battery should be replaced.
Tomorrow, I'm going to do this:
1. Clean battery terminals and check to see if diconnecting/reconnecting terminals resets something in the system.
2. Check voltage on the battery with my multimeter.
3. If the system doesn't reset, I'm going to hook a charger to the battery and see if the additional voltage changes anything.
I can't imagine anything just going out like that one day. I'm hoping it's just a voltage issue.
I'll keep you posted.