The oil pressure gauge in my 190D with the 2.5 turbo instantly moves to the top of the scale as soon as the key is turned on. It shows full pressure before the engine even begins to turn.

Any ideas or suggestions on what could cause this? What can be done to fix it?

__________________
.
1st MBz: 1982 300SD
2nd MBz: 1987 300SDL
3rd MBz: 1995 S420
4th MBz: 1987 190DT
5th MBz: 1984 300SD w/1983 300DT engine
6th MBz: 1999 C230k I'm 3rd owner, got it w/57,235 miles.
and manages Mom's 2007 R320 CDI