I have a 2000 jeep grand Cherokee 6 cylinder just replaced the head gaskets And now when i start my jeep it reads 0 oil pressure oil check gauges light on i changed the oil i changed the oil pressure sensor and still nothing the jeep runs great it only has 130k on it no knocking what else could it be? i didnt get a chance to check the pressure manually yet but i poped the valve cover off oil is going everywhere so that is good.

 

It sounds to me that you've got an electrical problem where the guage is not reading the sensor. Maybe you pinched or damaged the harness where it goes around behind the head or maybe the connecter at the sensor.

Another thing about these sensors. All the later sensors are digital-level circuits with a circuit board and piezo-electric crystal inside. Quality of manufacture is important so don't buy anything other that a Mopar sensor. I bought a Napa Premium sensor (made in Mexico) and it only reads 20 psi at any time. It reads 30 psi at -15*F.

I'd be willing to bet you've lost the electrical connection somehow. Check any engine to chassis ground straps for proper connections because being digital, it's only 5 volts.