Will 2012 Lexus RX 350 lock by itself?

If you push the unlock button and do not open the door within 30- 60- 90 seconds the doors will relock automatically. You can program in one of these times.

What about if I walk away from the car and totally forget?

Not exactly sure what you are asking, but here is a PDF of your lock system............ Access System with Elec. Key When unlocking the doors: Deactivates SmartAccess, only accessible using elec. key unlock button. = Off Use SmartAccess (touch door handle) or remote buttons. (Standard)= On 9. Auto Relock Time Adjust When the unlock button on the electronic key is pressed and the doors are not opened: The doors will automatically re-lock in 30 seconds. The doors will automatically re-lock in 60 seconds. (Standard) The doors will automatically re-lock in 120 seconds. 10. Lock/Unlock Answer Back Using the electronic key, the following functions can be programmed: Press the lock/unlock button and the system will not beep. = Off Press the lock/unlock button and the system will beep. (Standard) = On

My question: If I drive home, get out of the car, close the car door and go into the house, will the car know to lock itself after a period of time without me doing anything at all?

No. The locking event must be overt. I would prefer the option to leave doors open. If I got out for refueling or a quick stop to pick up dry cleaning I don't need the car to be locked nor do I need it locked in my home garage.

The car will not lock without user input....

Thank you everyone!

The answers so far doesn't fit my scenario. I have three cars in my garage, a 2010 RX350 a 2009 GS 350, and a 2011 Rava. For no reason at all, not carrying any keys in my pocket, all the cars would self-lock once in awhile. My wife has the same experience. Given that all 3 cars are locked simultaneously, the problem must be related to the remote receivers in the cars. The makers must have incorporated some kind of monitoring function that detects the presence of a possible bulgary. If so, Camery/Lexus need to provide a way to defeat this overzealous annoying protection that I don't need.

It doesn't make any sense, since my car has one key start. It will auto unlock when I open the door, get in, and start it, with car key in my purse. Then, when l left my car, It should Atuo lock with a certain distance or a certain period of time. Otherwise, I have to take out of my car key and lock it. That is how usually German Car works. So inconvenient of lock it myself, since it is one key start. I don't even need to take out my car key when I use the car, but need to when I leave my car. Wierd

Most cars will lock the door when you drive off but a car that just locked itself would lead to people being locked out of their car so I can't imagine any auto manufacturer would build in a "lock you out of the car" feature.

My 450h refused to lock with a wireless key inside the car, warning me of the key location (spouse left purse inside car). I haven't investigated whether there's an override for when that's your intention, as I grabbed the purse then locked the car.

The chip to open doors and ignition of my 2009 LEXUS RX 350 fell down. How can I get a replacement. I still have the key, but it only opens the door not the ignition. Any suggestions? Carlos Pacheco 571 228-0026

On my 2020 RX 350 I discovered that after you close your door and wait a few seconds, you can lock all doors by running your fingers along the bottom of the door handle.

Sometimes you parking the car by the street and you forgot to lock your car when you leave, ppl will try their luck to see if they can open the car to take your stuff inside the car, lately I found from my security couple times ppl even walk in my driveway try to get into my car during the midnight, if I forgot to lock the car, you can imagine what happen next , so I think it's necessary to have autolock function with on/off option, if you don't like it, you can leave it off, but don't say this is not making any sense.

by the way, most of car in nowadays will not lock the door if you leave the car key inside the car tho

I can relate to SeeEss. My Mazda MX-5 Miata is extremely convenient. I never have to use my key fob. When I use the door handle to open the locked driver's door, it automatically unlocks and opens the door. If I run to the store, once I get out of the car and close the door, as I walk away from the car to go into the store, the car doors automatically lock. Our Lexus RX 350 apparently doesn't have this very convenient, hands-off feature. Go figure...

My 2011 RX350 use to automatically lock when I turned off the car and left with the key. If I turned off the car and left with the key inside the car it would not lock. Why does it not lock when I turn it off get out with the key and walk away.

SeeEss i feel your pain. Not many people know of the auto walk-away lock feature as with Honda/Acura. When you exit the vehicle and all the doors are closed and you move the fob key away farther than 5 feet, the car will automatically lock. I have a alexus also and very annoying to remote lock or door dimple slide lock as I am used to my Acura walk away auto lock and have forgotten to lock my Lexus sometimes. Have been looking for aftermarket walk-away car lock, but doesn't exist.