Have started seeing an issue on my 2012 about few months already and the dealer could not even diagnose it because it is intermittent.

Sometimes when I arm the alarm, I can hear the actuators/solenoids cycle, but there is no single beep and the driver’s door invariably remains unlocked. Repeated press of the arm button on the fob would not change, i.e. vehicle remains unarmed and driver’s door remains unlocked. All the other doors are unaffected.

I can cycle through by pressing unlock once or twice, then the next relocking press would work. This is worrisome if I didn’t pay attention to the beep and thought the vehicle is locked while in fact it was not, this could also happen when the vehicle is at the dealership as the porter would think pressing the button would have locked the vehicle.

I can appreciate the dealer not able to fix a fault when they cannot isolate the cause, worse yet, it has yet to be replicated at the dealership and it would be unreasonable to expect the tech to test this continuously.

Any suggestion as to where to look? It would have been perfect if it simply fails 100%.

your door lock actuatior is going out, I had an IS350 and the drivers door started doing same thing, it stopped locking with the remote, I had to lock it by hand every time I got out and go through the pass dppr to unlock by hand until I got it repaired, but it started off doing it on and off at first.

Thanks for the confirm, I suppose I just have to wait till it fails completely because the vehicle has been "observed" during two separate visits and the problem cannot be replicated.