Mercedes A Klasse Transmission Issues

I had a similar issue with my old Volvo, although it was a different sensor. The symptoms you describe, especially the emergency mode and rough shifting, point towards the transmission issues being legit. It could be a faulty gearbox sensor, or like you suspect, low oil causing overheating problems. Check your transmission fluid level. If it's low, that might be your culprit.

When you say check the transmission fluid level, is that something I can easily do myself, or am I better off taking it to a shop? And with your Volvo, did the low fluid level cause the temperature sensor to fail completely, or did topping it off fix the problem?

Checking the transmission fluid level can be tricky depending on the car. Some have a dipstick, others don't and require specific tools. If you're not comfortable, it's best to take it to a workshop. In my Volvo's case, the low fluid level likely contributed to the transmission issues, but the oil sensor itself had failed. Replacing the sensor and topping off the fluid resolved the problem. A new gearbox sensor should fix it, if that's the issue.

Took it to a local shop, and you were spot on. Turns out the transmission oil level was indeed low, and the temperature sensor was faulty. They replaced the oil sensor, topped off the fluids, and cleared the codes. Cost me around 365€, but the car's shifting smoothly again, and no more warning lights! Appreciate the help!