The Oil Pressure Sensor (OPS) is a switch that receives a reference voltage from the Powertrain Control Module (PCM). To detect oil pressure, this switch is in direct contact with the oil circulating in the engine. When there are changes in oil pressure, the resistance of the switch rises or falls. These variations in resistance are interpreted by the PCM as a reasonable and accurate representation of the oil pressure.
There are vehicle models that have more than one oil pressure switch or sensor. Note that both sensors are not interchangeable, so they have different colors or other features with which they can be differentiated. You should check with your vehicle’s technical information to see if this applies.
Fault code P0520 OBDII is set when the PCM detects an out-of-range signal voltage at the OPS sensor or its circuitry. This means that there is abnormal oil pressure. Possibly, this code may be accompanied by code P2105 which indicates that the PCM has started a forced engine shutdown to protect the engine. Therefore, you may have to solve the code P0520 OBD2 to restart the engine.