14 year old models use specific diag partition and it cannot be recreated once removed.  This is also why Dell made ISO files for the diag partition as well as installers to put them on FAT16  usb flash drives. Note: To run this tool, you will need a USB key formatted to FAT16 with a maximum size of 2GB.  That is why they made CD ISO to F12 boot from. [URL] Dell 32-bit Diagnostics A1220   [URL]          
Hi, I have an Optiplex 330 with 2GB of RAM, a 500GB HDD, and a GeForce 730 GPU. I am wondering how I can make the utility partition from scratch as it is not detected, I am running endeavourOS (Linux, Arch based) and would like to repartition enough space for it in order to have the utility again.   Thanks! -Henry
Dell Diagnostic Utility Partition