I had my 2006 R class at the dealer for a bunch of things, including a B service, and a battery replacement. It was not cheap.

The next day? Came off the highway, was on the local roads, and leaving a stop light the car went into limp mode. No codes, just suddenly could not get out of its way, and the engine wanted to hit very high revs.

I pulled over, turned it off, let it sit for a few minutes, and when I restarted it was fine.

Do I go back to the dealer and wind up paying who knows what to repair who knows what? Or do I figure it's a computer glitch and it won't happen again? Or do I say to the dealer "hey did you NOT check codes etc while it was on the lift"?

I'm just not sure what to do. I'm not in the mood to pay yet more on this car. It only had 50,000 miles on it, almost all highway.

My car went to limp mode once about 2-3 years ago and it went away and have not came back. Took it to the dealer afterward and they could not even see the code from the computer.

If no lights/warnings on now, codes have cleared. If occurs again, I would for sure take it to get fixed. Just don't turn off car, as it will clear codes. It sounds like the beginning of a sensor failure.

If a fault occurs, it will be stored in the control module until erased via SDS/scanner. Even disconnecting the battery will not clear the code. It sounds like your internal turbine speed sensor is going out in your transmission. The transmission control module sees the sensor malfunctioning for a long enough period to going into limp home mode to prevent damage. To fix this the conductor plate on top of the valve body will have to be replaced. You will HAVE to bring it to the dealership for this repair. Even for customer pay repairs for this require the technicians to send paperwork to a "diagnosis verification" department just to order the part. If you have an ELW or CPO it should be covered.