I have recently run into this issue. If I turn off the car, the system is not turning completely off. If I had the AC turned on, the light will still be illuminated after taking the key out, and an audible buzzing sound can be detected until pressing the button and disabling the AC (all while the car is off). The P light on the gear shifter stays illuminated all the time as well, and I thought I remember that turning off after a few moments of powering down. I have no idea what is happening and I really don't want the car to end up bricked. Any ideas? I am at 18800 miles, second owner. It is old enough it is probably not covered under warranty anymore unfortunately.