A Chevrolet oil pressure sending unit is a type of car part that sends oil pressure information from the engine to a gauge or light on the vehicle's dashboard. When the oil pressure rises, the needle on the oil pressure gauge moves toward the right, and it moves to the left when the oil pressure decreases. When the oil pressure becomes too low for safe operation, the pressure sending unit turns on a warning light on the instrument panel.
Early oil pressure sending units attached directly to the engine's oil pump. These units used pressure differences in the oil system to send a reading to the instrument panel. While very simple to install and operate, these early oil pressure sending units were not very accurate, and most have been supplanted by more modern units.
Modern oil pressure sending units are little more than electronic transponders that only transmit information, instead of collecting the data itself. These oil pressure sending units attach to the vehicle's oil pressure sensor. The oil pressure sensor, also called the oil pressure switch, is another electrical component that usually attaches both to the sending unit and the oil filter. The oil pressure sensor monitors real-time pressure information and sends this data to the sending unit, which then sends the data to the instrument panel, keeping the driver informed.