2002 Pontiac Bonneville oil pressure constantly reads 120 psi.

The oil pressure sensor is usually near the oil filter. Easiest is to get a new one so you can see what you're looking for. It will have a three-wire plug. Unplug the sensor, then see what happens to the gauge. If it drops to "0", replace the sensor. If it stays high, the gauge could be defective or the wire going to it is grounded.

I found a sensor near the power steering pump with a 2 wire connection. It took a 1 1/16 deep well socket to get it out. what sensor is this? Am I close to the oil pressure sensor? Im parting out the car and have 3 other Bonnevilles. Thanks. Mike

Everything I found shows a three-wire sensor for the oil pressure. A two-wire sensor is going to be either a single on / off switch, a double on / off switch, or a temperature sensor. Look at the business end of it. If you see a tiny hole in the middle, it's a pressure sensor. If it's solid on the end, it's a temperature sensor. Those typically have a round piece, usually gold or tan-colored, about 1/4" in diameter and about 1/2" long.

If you can post a photo, I might be able to tell for sure what you have. You might also try the Rock Auto web site and look up various sensors to see if you can match it to something.

As a general rule, temperature sensors sit in the cooling system, usually on the cylinder head on four-cylinder engines and on the intake manifold on V-type engines. There's two of them and they're closer to the thermostat housing at the end of the upper radiator hose.

Oil pressure sensors have to be screwed into an oil passage where the oil is under pressure, and there's none of those in an intake manifold. These are generally close to the oil filter or the oil pump when the front engine cover is the oil pump housing.