The oil pressure sensor on a Chevrolet 4.3L V6 engine is part of a network of sensors that provides the powertrain control module (PCM) with information about the engine. This sensor measures the pressure of the engine oil and relays this data to the PCM. When the PCM detects low oil pressure it illuminates the oil pressure light. As time passes, the oil pressure sensor may develop an oil leak or begin providing the PCM with inaccurate pressure information, necessitating its replacement. New oil pressure sensors can be purchased from automotive parts stores and Chevrolet dealerships.
Locate the oil pressure sensor. It is on the right side of the engine, just below the intake manifold. It is approximately 3-inches long and is made from black plastic. A two-wire electrical connector is attached to the end of the sensor.