The car is a 2018 C43 AMG with 64500 miles. Few days ago I went out to move my car but my keyfob was dead, started the car, go into reverse and car moves to neutral. I went to drive, car goes to neutral, after a bit it left me move it, and i did some googling and found out that it could've been because of my dead keyfob (I put the key into the starter, not push to start because key was dead). After this nothing happened until today.

Today, driving along fine, get home, try and park, put the car in reverse to get into the driveway, and the car jerks while stationary, move a little bit in reverse and it moves to neutral, try and go to drive and it moves to neutral happened about 4-5 times before it let me and then a check engine light comes on after i restart the car. I used by scanner it it threw a p073e code, and it says car can't engage reverse on the scanner. Unsure when the last transmission service was done but I've only owned it for about a few months now, Would getting a transmission fluid flush and change relieve this? Also what are the costs I can expect for that service.

Thanks

No, the dead key fob likely has nothing to do with it. You get this error if the transmission is not holding the reverse gear. One possible cause is low transmission fluid level, so the transmission fails to generate enough pressure to hold the gear. However if that's the case I would also expect that you have issues in the forward gears as well. So the next possible cause is the solenoid for the reverse gear failing, not holding the necessary valves in the required position or a faulty/clogged valve. Could be the solenoid itself having failed or an electrical issue with the wiring. Next up would be the transmission control module having failed and worst case an internal mechanical issue. Cost kinda goes up in that order. Low fluid is easy to correct, but after that things gonna have to be taken apart, starting with the valve body if a valve or solenoid is faulty all the way to taking engine/transmission out and open up the transmission if it's an internal mechanical failure, but at that point a dealership will say you need a new transmission, because they don't rebuild transmissions. Even if the valve body failed, they might just say you need a new transmission. At that point you'll be better off taking it to a transmission shop that is experienced with these transmissions and can rebuild it.

Thank you for replying.

I haven't had any issues shifting (my dumbass forgot to mention that in the original post) ,and car goes through gears nicely, I only have problems when going from park - drive - reverse. I will head to a shop and get a diagnostic done, here's to it being only fluid!
Also I've noticed you a lot on this forum you contribute a lot! Thanks!

Fluid is due every 5 years or 50,000-60,000 miles whichever comes first, I did mine at the 5 year mark, I have a 2017.

Ya good troubleshooting steps, definitely recommend OP to do the fluid first. Assuming the car never had it done yet.

Update: got the fluids change and just my luck that it wasn't the issue. The tech said that it's most likely the valve body needing replacement apparently? He's gonna check with MB and order the part and tell me the cost. The check engine light keeps going away and coming back and I didn't realize this before but I can't go above 5th gear and go below 3rd most of the time. Still doesn't wanna engage reverse or drive until changing it about a few times which sucks.

Yep, that sounds like the valve body is on the fritz. The transmission control module, pump, valves are all in there, so that's the brain of the transmission. Short of there being a mechanical issue in the gearbox itself, hopefully that resolves your issue.

Getting that replaced, fixed my issue with shifting in P,R,N and D. But I had to get a full trans fluid flush because after getting the valvebody job done. ($2750) I had to get a full trans fluid flush because I started slipping gears BADLY. But this ultimately fixed my issues with the transmission. I have been hearing a weird sound from going to D - R or R - D but I think that's just a quirk from the trans getting adjusted to new fluid.

Can you record that weird sound and upload it to youtube or something?

The sound went away, but it sounded like needing new brakes almost, not the squeaking, but the clunking

Good to hear the weird sound gone away : )

If you had an independent replace the valve body and conductor plate, did they also do an adaptation of the transmission? If not, you will probably experience some harsh shifting until the tranny adapts. This may be the clunking you initially experienced.