So about a year ago i had some a knocking/ rattle when running. I thought it might be the oil pump so got all the parts. Took it to my mechanic he told me it was the fly wheel. so i had him replace the oil pump while he pulled the engine. Had problems when i got it back major loss in mpg. 6 months later i replaced the crankshaft sensor. Month or so later i got a gm dtc 19 code figured it out it was the oil pressure switch. Replaced that worked great for 2 months and now i get the code again. i don't know if the fuel pump is on this circuit i saw a article that the fuel pump (shorted) was on this circuit. But i don't know if that is true for this car.

19 crank sensor circuit fault

Could be a loose connection at the CPS, or if you bought an inexpensive aftermarket sensor it could be acting up. Don't know what this code has to do with the oil pressure switch.

AFAIK, the oil pressure switch is supposed to disable the fuel pump on startup if the sensor doesn't see oil pressure build up during the cranking phase. On some vehicles the ECM will allow the engine to attempt to start without a signal from the crank sensor.

If you bought a non-OEM sensor, it is most likely refurbished, and some brands are better than others at the remanufacturing process; others, their QC is severely lacking.

We'll I don't know either but when the car shuts Dow and won't start back up. I unplug the oil pressure switch and plug it back in and it starts. If I were to unplug and plug the crankshaft sensor it would not start.

I bought the oil pressure switch from dealer and crank i got the one with a lifetime warranty and it wasn't the cheaper one.

try cleaning the oil connector and see if the wires are loose in the plug

the pump relay is controlled by the pcm, it primes the pump and then turns back on after it gets a signal from the crank sensor. the oil switch is a redundant secondary circuit to keep the engine going if your pcm/relay/wiring on that circuit has an issue. you should have 12v on the gray wire while the pcm is priming the pump then nothing until the engine starts

So I was doing some searching today on the car. I found a bad fuse for the injectors/ fuel pump. So I replaced it now I get the pump to run with the ignition on but it will not start still. Now if I unplug the oil pressure switch, it primes normal and starts as well as the check engine light goes out.

I did try replugging the sensor back in while it was running and it shut the car down. I triple checked the old plug to the new and all wires line up. Any suggestions?