2000 Chevy Corvette 0il pressure

my 2000 corvette has a problem with oil pressure or the oil pressure gauge.I think its the gauge. when I turn the switch on the needle goes all the way to 80 psi even without the engine running. when I check the pressure using the computer its said 130 psi and thats still without the engine running. I know that its impossible to have oil pressure without the engine running. I would like to know whats my problem? have anyone else encountered this with a LS1 vette engine? Is it the gauge? Is it a sensor? 0r what?somebody please tell me