Hello guys, I have an M56X 2012 model Tech package 41k miles. Randomly yesterday I approached the car and i was unable to unlock the door thru the door knob, or (intelli-key). Tried using the fob to unlock and it wasn't reading it for the first few tries and then it finally opened. Tried starting the car, it started then immediately stalls off. Did that a few times, as well as held the fob over start button to see if it reads it, started but yet it stalls again. 10 mins later after replacing the fob battery it continued to start and stall, but the lock and unlock worked more accurately. Called for tow service, an hour later while waiting for tow service I made another attempt to start the car and it starts right up as if there wasn't an issue before

Does anyone have any clue what happened here??

Sounds like a marginal battery. Once you get the car running you get enough surface charge to gets your electronics going again, but when the car sets in a non charge state you get enough discharge to cause your electronic problems.

The dealer will probably check your battery and let you know for sure.

Did you try with the second key fob? Also make sure the battery terminal are on tight.

Thanks for the input guys. The car has been starting fine since. I have scheduled an appt for saturday morning.

It's not the remote battery or the car battery -- something else is going on. There are too many of us on here having the same issue for it to be a coincidence. If you find out what the issue is let us know. I'm having the issue myself, usually on cold days. If it happens to you again give the car some gas while starting and it will start right up. Not the best fix, but a usable workaround until we can find out what's wrong. I'm going to mention it to the dealer the next time I put my car in the shop.

Your problem was actually twofold, ka -- you had a bad key fob battery which you fixed and the second issue which is TBD.

Took it to the dealer today and they said it was the computer system needed an update that they've recently received. I left there everything was fine. stopped here and there. As soon as I take my girlfriend to lunch, we get in the car, I attempted to start the car..... The usual rev, Gages go up and come back down..... Wait for it..... The cars startles with an attempt to shut down again. This time it didn't stall off.

Glad it worked out for you. Do you have any info on the update? Was it an ITB? any info I can take to the dealer would be greatly appreciated.

Same problem here.. 2012 M56x with tech package, and it starts and stalls on cold days. I've been having the issue for 2 winters now..
Dealer couldn't get my car to start for almost 4 weeks last year.. they kept it for 4 weeks and couldn't figure it out, and then when it warmed up the problem went away..
This year I have the same problem, less frequently, but it's to the point that I'm afraid to go anywhere with the car in the cold (below freezing).. so when I do I just leave it running for fear it wont start.
No idea what the problem is, but this seems to be widespread!
My guess is that the problem is something to do with whatever senses the temperature to adjust the fuel/air mix.. part of the fuel injection system. Just a guess..
I also have a 2012 QX56, and have had the oil pump / timing chain 'thing' fixed/replaced on both.. but only have this issue on my M