p1635 00 bonneville ssei
 

hope somebody can help me figure this out. So not to confuse you the problem is the MIL. The code is P1635 which my scanner tells me is a 5 voltage reference 1 circuit. this is just a autoscanner plus with code connect. when I look up top reported fixes they are replace fuel pump , replace map sensor , and repaired powertrain control module connector. In that order. so you know , while replacing the #6 injector in an attempt to solve a slight miss problem I have had since I bought the car 6 months ago, I unplugged the MAP and control mod, as well as broke and repaired a vacume line, and I also unplugged most everything in that area to get the back side fuel rail up far enough to R&R that injector. Well it did not solve the problem and now I have this code. Further more I have noticed my oil pressure gauge drops to 0 and back up to around 50 as well. the oil sender/ sensor was replaced a few months ago , but I replaced it again under warranty. I am not sure if I am acually loosing oil pressure or the gauge is reading incorrect. I think I need to start testing some wires to see which one I messed up but don't know where to start. so anyway if you have any thoughts on this and/or a wiring schematic that would be great.

This code seems to be gone now but the oil pressure gage is still eratic?

Best way to eliminate the gauge is to watch live data via a scanner and or hook a mechanical gauge up to the engine. The 2000+ Bonneville's tend to have issues with the clusters.