Diagnosis
A flashing yellow light is a warning state. It means the AutoDos system has detected an irregularity—usually that the PowerDisk cartridge is very low, or there's a minor communication glitch between the cartridge reader and the main board.
How to Fix It
The first thing to try is reseating the cartridge. Open the compartment door, take the PowerDisk out, and put it back in, making sure you push it all the way in until it clicks firmly. Close the door and wait a minute. The light should re-sync and ideally turn solid green. If it stays yellow, check the Miele app; it might give a more specific warning like "Cartridge low" and prompt you to order a new one.
If That Didn't Work
Try a system reset for the AutoDos. In the settings menu (wrench icon) on the dishwasher's display, go to "AutoDos" and select "Reset." Confirm. This clears any temporary errors. After it reboots, reinsert the cartridge. If the light is still yellow, the RFID chip on the cartridge might be damaged or unreadable—try a different, new cartridge if you have one.
Heads Up
A yellow light doesn't stop the dishwasher from running. It will use detergent from the separate manual compartment (if filled) or default to a generic dose. But you won't get the optimized cleaning for the selected cycle until it's back to green.