I'm somewhat surprised that folks would leave a Bluetooth code reader/scanner plugged into the OBD2 port. I've also got a Bluetooth code reader/scanner (BlueDriver) and it stays in my console in case I need to use it when "out & about". It connects to my Cell phone (which I nearly always have) and/or to my tablet (which I take on trips). Just doesn't make sense to me to leave it plugged into the OBD2 port.

I seem to recall that the BlueDriver powers up immediately after it is plugged into the OBD2 port. By powering up, I mean it begins searching for a Bluetooth device to connect to. Maybe it will pull a drain on the battery if left plugged into the OBD2 port. But I think as long as it can't find a Bluetooth device to link to, it won't stay on. But these days, there is always a Bluetooth device somewhere nearby - the device just isn't able to connect because of a lack of authorization and software. But it may keep looking! Others say it won't consume power unless ignition is in "power on" position. Gotta go back & read the paperwork for the device now - I'm curious.