I had thought this was virtually impossible. I have tried numerous times to lock the doors of my 2014 Honda Pilot while one door was open, It does not matter which door, if you use the key fob or the door lock button, the locks don't activate. Normally everyone is getting out and if you try unsuccessfully to lock the car, before the last door is closed...
Yesterday I was at the lake, tossed my keys on the floor of the car (so they would not get wet) pushed the lock button on the drivers door and closed the door, all in one nice fluid motion. As I looked at my keys laying on the floor as the door shut, I was think I am so glad this is Honda so I can't lock myself out. But when I grabbed the handle to open the door, it was locked!
I have tried a to recreate and have not been able to. If you push the lock button with the door open, it does not lock.
How could this happen?