I can’t say that it’s causation and not correlation, but I got my oil changed and now my doors of my 2017 nx200t will automatically lock with or without the key inside after I turn the car off.

I first discovered this to my dismay with the key in the car. Fortunately I was at home and have a second key. Then I thought it was related to that first key, so I started regularly using the second key. Nothing changed, the car keeps doing it!

With or without the key in the car, the doors automatically lock after it’s been parked and turned off for a few minutes.

What is going on?? A quick google search has me thinking that the Lexus can’t do this today, although people actually want this feature!

 

If the answer to this question is "yes", then I am on the sire of causation .
During the oil change, or shortly before or after, did any other person drive or move your NX?

The door lock push buttons located in the driver and passenger armrests override all of the anti-lockout provisions designed into the vehicle. They need to be functional in case an emergency exit situation should arise. Someone could have accidentally damaged the drivers armrest switch, and the "lock" button is partially depressed. You can eliminate this as a cause by prying off the entire switch bezel and temporarily disconnecting the connector for the window and door lock switches (mirror switch has a separate connector).

If not sure how to do this, look for a YouTube video, or I can post some photos. It takes less than 30 seconds to remove the bezel, then perhaps another minute to withdraw the connector.