Hi,
I am new in the forum, but this is my 3-rd old Mercedes over the years, and I often checked here to see for solutions of the common issues.
Currently I am having this red warning message on the dashboard:

Brake service
BRAKE
Stop, Call Service

accompanied by ABS light and code 0120 - accelerator pedal sensor circuit A error, resulting in some kind of LIMP mode - car wouldn't run more than 2000 RPM and more than 30MPH downhill.

Here is the sequence how it all happened:
1. I got regular message for brake wear and I changed the front rotors, sensor wires and pads (with cheaper ones from Rockauto);
2. I drove the car for 17 miles and felt some skip (jerk) between 60 and 70 mph - I believe that produced the 0120 code - pedal sensor fault;
3. I changed my 4 tires that same day.

After changing the tires, driving out of the tire place, I got the red message, turn around told the guys and by the look on their faces understood that they wouldn't be able to fix it. So I drove to my mechanic - down the street.
He reset the computer, light went away for about 2 miles and came back. I drove home limping and that was 1 week ago.
Since then I am trying to fix it.
Here is what I have done so far:
1. Changed the rear rotors, pads and sensor wire;
2. Installed new gas pedal;
3. Replace the brake light switch
4. Checked the tire pressures and adjust them to spec (found front left tire to be around 50 PSI)
5. Reset with OBD2 cheap scaner
6. Tried to reset ECU 2min with gas pedal down, 5 min contemplating thing
7. Reset Comand - Mute+1+3
8. Drove the car around the block

Now I am running out of ideas, and that's not good!
Please share with me your thoughts and advice me what to do next!
I am aware of the Dealer ability to hook the car to Star Das - but that would be my last option.
Thanks!
Best Regards!

 

I kinda have the same problem that you have. My 2003 goes into limp mode on and off as I come to a complete stop.( it seems like) Not all the time but has been more than usual. I believe mine give me a code like P705 transmission range sensor. I’m out of ideas but buying a new shifter from dealer for $1600. Not looking to spend over $ 2000 just yet. Any ideas???