I was reading this: http://www.bimmerfest.com/forums/sho...passenger+seat
then I realized that I get "High Battery Drain" message sometimes. Because this message doesn't come out too often, I chose to ignore it. However, I do get the following experience with the battery:
when I sit in the car, and turn everything off, every few minutes, the CD starts to roll and I can hear some equipments start to run...is this normal?
Is that like the car detects you sitting in the seat, so turn on some equipments? Or this should not happen?

What is supposed to wake it up in normal situation?

Thank you.

 

From my understanding the first module that awakes the car is activated as soon as it detects the doors being unlocked.

 

same as my understanding.

 

If you sit in your car and switch everything off, after a minute or two the car will close all the air vents inside/behind the dashboard...maybe this is what you hear.

 

Yup, also its switches the fuel pump off as well.

 

do you have comfort access option? that could be one of the culprits...so i've heard.

 

Yep, mine has comfort access. I don't think it is closing the vents. It happens constantly, not only once.

 

Had the same problem... in the end it was a faulty comfort access sensor. If you have a comfort access sensor not working, it is most likely the culprit. Easy way to test this is by disconnecting it and see if the problem goes away

 

Is it the one box below the spare tire?

 

The sensors are in each of the doors and the trunk. If you have the key in your pocket, does comfort access work in all the doors? What I mean is that when the car is locked, can you unlock it from all the door handles? If you can't from one, then you know which sensor is shot.