super high oil pressure?

Can someone please lend me some advice.
I just replaced a blown engine for my girlfriend (2.5L), and the deal is the oil pressure guage is maxed out. The engine runs great, but I don't know what this could be? electrical? bad sensor? what? and could this be very bad for the car?

I does not fluctuat except that it goes from 0 to 80 in under 1/2 sec.
Any advise is greatly appreciated.

It sounds like it could be a bad sending unit.What is it reading with the key on engine not running?If it goes to 80 it's probably an open circuit,like not plugged in or a bad sending unit.

Remove the sending unit, attach a mechanical oil pressure guage to it to get a "true" pressure reading. I agree with xj31, sounds like a bad sending unit. But check the pressure to be certian it is within limits. Where did you get the engine from?