SL Transmission Problem and Solution

A faulty transmission sensor is certainly a plausible culprit for the symptoms you describe. I've experienced similar transmission issues on my SL. Have you checked the gearbox oil level? A low oil level can trigger all sorts of gremlins in the 7G-Tronic transmission, including those error codes and that unsettling emergency mode. Also, what error codes are you seeing?

I haven't checked the oil level yet. Where exactly is the fill point and how do I check it? Also, I don't have the error codes right now, but I can get them scanned again.

It's located on the transmission itself; however, accessing it and properly checking the level requires specific tools and knowledge of the correct procedure. Given the symptoms and the potential for further damage, I strongly advise taking it to a qualified workshop. They can properly diagnose the issue, check the oil level, read the error codes, and determine if it's the gearbox sensor or something else entirely. The grinding noises are particularly concerning; continuing to drive it could exacerbate the problem.

Thanks, I appreciate the advice. I took it to a workshop, and it turned out the transmission oil level was indeed too low, causing the transmission oil temperature sensor to throw errors. Repair cost was 365€. They topped it up and replaced the sensor. Seems to be shifting smoothly now.