Yellow Exclamation Mark Prius. It may go away on its own after a few restarts. That yellow triangle is the only thing that might tell you your oil is low.
This sign will appear on the packages which contains classes with warnings (like unused imports, unused variables, using raw types, etc.).
The yellow exclamation mark provides an indication of a device's current status and could mean that there's a system resource conflict, a driver Unfortunately, the yellow mark itself doesn't give you any valuable information but what it does do is confirm that something called a Device Manager error code.
For instructions on how to turn it on, refer to this link. Have serveral yellow exclamation marks showing up on there network adapters in bottom right corner of there windows desktop and saying. If your inquiry is about the yellow exclamation mark on the C: drive, it means that you haven't completed the BitLocker encryption process.