Sprinter automatic transmission issue

The symptoms suggest an issue with the transmission oil temperature sensor. It's like your Sprinter has a fever, and the sensor is communicating this. Grinding and slipping could be from the transmission not getting correct oil temperature info, affecting gear shifts. Before replacing the sensor, check the gearbox oil level. Low oil can cause similar symptoms and trigger the temperature sensor error. Check that first.

Thanks for the quick reply. How do I properly check the gearbox oil level? Is it straightforward, or does it require special tools or knowledge? I'm hesitant to do it myself if it risks causing more damage.

Checking the transmission fluid level on your Sprinter isn't simple like checking engine oil. It needs a transmission dipstick, checking the level with the engine running and the transmission at a specific temperature. Given your concerns and the potential for issues, I recommend taking it to a mechanic specializing in automatic transmission repair. They can accurately diagnose the issue and advise on the necessary transmission repair. It's better to spend a little now on a proper diagnosis than risk more damage and a larger bill later.

Thanks for the advice. I took the Sprinter to a workshop. They confirmed the transmission oil level was low and the gearbox sensor was faulty. They replaced the sensor, topped off the fluid, and cleared the error codes. The transmission repair cost 365€. The engine warning light is off, and the transmission shifts smoothly again. Thanks for your help.