Low lube oil pressure:

Low oil pressure or loss of oil pressure could destroy an engine in short order. Thus, most medium to larger engines will stop upon low or loss of oil pressure. Loss of oil pressure could result in the engine seizing because of lack of lubrication. Engines along with mechanical-hydraulic governors will also stop due to the lack of oil to the governor. The oil pressure sensor commonly stops the engine. The oil pressure sensors on larger engines commonly have two low pressure setpoints. A single setpoint gives early warning of abnormal oil pressure and an alarm function only.

High crankcase pressure:

The second setpoint could be set to shutdown the engine before permanent damage is completed. High crankcase pressure is commonly caused through excessive blow-by (gas pressure in the cylinder blowing through the piston rings and into the crankcase). The high pressure condition denotes the engine is in poor condition. The high crankcase pressure is commonly used only as an alarm function.