Hello!
I have lost my only key to my Lexus RX 350 2012. It is possible that it is in my car, but I’m not sure how to find out if it is? Does anyone happen to know what alerts the car gives if you try to open the door? Any advice would be greatly appreciated thank you so much!

 

Go to a Lexus dealer with proof of ownership and they can cut you a key.

 

If you can start the car, generally the key would be in the car. So that's one way to check.

Usually it won't let you lock the doors if the key is inside the car, can't remember specifically with the 2012 though, may need to move to the RX specific forum.