Engine Oil Pressure Switch (2.0L Engine)
WARNING: This page is about a different car, the 2018 Lincoln MKC. However, it is still accessible from the selected car via links, so may be relevant.
The oil pressure sensor is hardwired to the PCM through VREF, signal and return circuits. The PCM provides the sensor voltage supply on the VREF circuit and monitors the voltage changes though the signal and return circuits as the oil pressure changes.