Hi everyone just wanted to see if anyone knew what could be the issue. My car has been working perfectly fine but 2 days ago i was shifting from park into drive and it just shut off the engine completely. I thought it was something with the transmission or maybe intake was lose but checked the intake and it was fine so i then had it towed to my local shop. They ran diagnostics on it and there was absolutely no error codes. Car does not go into gear whether its drive or reverse and i have absolutely no idea what could be the issue. I thought it was the TCM but that doesnt look to be the issue.

Any advice would be amazing thank you in advance

Start with real diagnosis. Clearly the corner garage isn't up for it.

Not corner garage. Its a legit shop and they're running Xentry and Starr. I'm actually happy its not a crazy transmission code because now im thinking its probably some dumb lose cable or some simple thing like that lol. That's why i wanted to see if anyone had the same issue in the past as it doesn't seem to actually be a drivetrain issue.

I've had intermittent issues with 'ask the shift lever for park' and it doesn't respond. A couple of times the shift lever is asked to go into drive or reverse with no response. Very intermittent. I got a code for the shift lever.

Your description sounds of a relay taking a nap briefly.

Sorry.... No first or even second hand knowledge of what you describe.

What year and milieage, and do you have any tunes? Also, have you had any recent work done on the car? Can you share any other information that would be helpful? Your issue could be something as simple as a brake pedal switch, which makes sure the brake pedal is depressed prior to going into gear, that's not working properly. But normally the car won't start with a defective pedal switch so it might not be the problem in your case.

This is actually a great lead thank you!

2015 S63 63k Miles. Stage 2 Tune and exhaust catless straight pipe work done. O2 and back pressure is well managed and properly tuned. Turbos are secure as well.

Yeah, sounds like your gear lever isn't registering the gear selection at all. I would otherwise expect codes. The transmission itself communicates directly via the CAN bus, so if that communication was interrupted, you'd get communication error codes. Similarly, if the signal reaches the TCU, but something is wrong in the transmission, then I would also expect error codes as sensors would detect that things aren't engaging as they should. Since you get nothing at all, it does sound like the issue is upstream. I don't think it's the brake pedal sensor, because you'd get a message in the instrument cluster telling you that you need to put your foot on the brake to select a gear if you attempt to select it and it thinks the brake pedal isn't pressed. And as said above, the engine wouldn't even start.

Just to test the communication a bit. Can you press M to put the transmission in manual mode, and do you see it acknowledge in the instrument cluster, and can you change drive modes? Any error codes thrown when you do any of that?

Right now it's in the shop and they are going to put it on a lift shortly as they just scanned it yesterday as the shop was closed when the vehicle arrived. From what i was doing to debug the issue I was changing between different drive modes to get it to work. So cycling between Comfort/Sport and Manual and in Manual I was trying to rev RPMS to around 1500-2000 to get it to engage and move the car but it didnt work. The tow truck driver was able to use the same method to get it into reverse and actually get it to move thankfully because i was stuck in a weird spot in a gas station lol.

Where the shift lever is having an issue there *should be codes for that too.

Theory and practice.

There's a lot that happens in between selecting a gear and the car moving forward in modern vehicles. I just want to be clear about what you are describing in order to isolate the failure point(s). If you don't mind, can you describe things in a more granular fashion?
When you select the gear, does the car recognize the gear change in the instrument cluster?
If so, do you feel what you normally feel when selecting a gear? My 18 S63 will sometimes give me the flex plate bump, maybe 1 out of 10 times, but more often when selecting a gear when the RPMs are above 800. I do the stupid thing where I sometimes shift into reverse before coming to a complete stop.I know its a bad habit but when I'm home I just want to get into the garage as soon as possible.
Is the EPB disengaging normally?
Do you feel any engagement in a selected gear when pressing the accelerator pedal? If so, at what RPM?
Are you feeling any resistance to forward movement?
Will the car move in any direction, even a couple inches, at higher RPMs.
Any accompanying sounds that aren't normal?

When was the last time you changed your trany fluid, and how much was put in?

Try unhooking the battery over night with the key on engine off. Or try unplugging ISM on side of transmission driver side of case. May have to remove a shield to access plug.