If your vehicle is showing oil pressure gauge reads unusually low, here are the most likely causes and the parts you'll need to fix each one.
The most common reason for a low oil pressure reading is simply not having enough oil in the oil pan due to leaks or normal consumption. Without enough oil, the pump sucks in air, causing pressure to drop.
The sensor that measures oil pressure frequently fails, clogs with sludge, or develops a poor electrical connection. This causes the gauge to read low or zero even when the engine has perfect oil pressure.
Using an oil viscosity that is too thin for the engine, or running oil that is heavily degraded and diluted with fuel, will cause lower pressure readings, especially when the engine is hot.
A severely clogged oil filter or a filter with a defective internal bypass valve can restrict oil flow. This is often caused by extending oil change intervals too far or using poor-quality filters.
Internal engine wear increases the clearances between bearings, allowing oil to escape too quickly and dropping system pressure. Alternatively, the oil pump itself may be worn out and failing to generate flow.