Sometimes a low engine oil level can cause low oil pressure because there's not enough oil in the oil pan for the engine to pick up and send through the engine.
If the oil level is low then adding the engine oil to fill the oil pan back up to the full mark can sometimes fix the low oil pressure.
Other times the oil pressure being low could be caused by something else or the oil pressure may not even be low but instead the oil pressure sending unit could be bad.
Oil pressure being low can be caused by a number of different things and sometimes it can be a serious problem that is causing the low oil pressure and other times it can be caused by something less serious.
If your oil and oil filter has not been changed in 5,000 miles or more and you suddenly developed low oil pressure then the oil pressure being low could be caused by the clogged oil filter.
Also when oil gets older in the engine and becomes contaminated the oil can become thinner which can be a cause of low oil pressure.
So if your oil needs changed then sometimes then changing the oil can help increase your oil pressure.
Your oil pressure should be between 45 to 55 PSI when the engines RPM goes up and at least 25 PSI when the engine is idling.
Other causes of low oil pressure are worn engine bearings, clogged oil pump strainer, bad oil pump or even just too thin of oil.
The oil pump rarely fails though but it can.
Sometimes it's also the oil pressure relief valve on the oil pump.
Another thing to check is the oil pressure sender unit that can fail and not send the proper signal to the oil pressure gauge.