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There are several things that can cause low oil pressure. I will list them for you. First is the oil filter, oil pump and oil pick up tube. Next is the connecting rod and main crankshaft bearings might have spun. This will usually have a noise as well. Next is the engine block and it might have sludge in it or a restricted oil passage. Next it might just be the sensor itself. If you have low oil pressure in the engine you should have a lifter noise. If you dont have any noises then mostly likely it is the switch. The only other thing that might cause low oil pressure is a collapsed lifter. Let me know if you have any other questions and if I can help.