DTC P1189: Engine Oil Pressure Switch Signal Circuit: Description

Engine oil pressure switch is a normally closed switch that opens with the proper oil pressure. With ignition on, and engine off, PCM should detect a low signal voltage input. With engine running, pressure switch opens and PCM should detect a high signal voltage input. PCM tests the state of the engine oil pressure circuit with ignition on, and engine off. If PCM detects a high voltage input on engine oil pressure signal circuit, DTC will set.