Why does the trunk of a Lexus RX 350 open randomly by itself even when the car is locked?

Answer 1

The button on the remote control may getting pressed inadvertently by keys or other objects in your purse or pocket. This may be relevant if the opening of the trunk happens when the remote control is within 100 ft (30 m) of the vehicle, i.e., within radio range. (The distance may vary, depending on nearby obstructions and interfering electrical signals.)

To eliminate the remote control as the source of the problem, store it in a manner that prevents the buttons from being pressed accidentally and see if the trunk still opens randomly on its own. One could also completely wrap the remote control in aluminum foil during the test period, to prevent radio emissions if the control is malfunctioning and sporadically transmitting even if a button isn't pressed. Removing the batteries from the remote control is not a good idea, as most modern electronic lock systems use a "rolling code" security scheme, and removing power from the remote can cause it to lose synchronization with the receiver in the car and would require re-training the system after the batteries are reinstalled.