I have a PowerEdge R520 with this error and found a thread here with a solution which includes taking the server to minimum configuration. The thread,
"VLT0204 System board PS2 PG Fail voltage is outside of range. Contact support"
has the user going to minimum and rebuilding, clearing the error but not revealing any failing component.
I would just like to know if there is not a way to diagnose and clear this error without taking my server out of production. This is just a cya as my boss looked incredulous when I told him we had to take it to minimum to clear this error. Thanks.