DTC P0191-85: Fuel Rail Pressure Sensor Circuit Range/Performance: General Description

Installed on the delivery pipe, the Rail Pressure Sensor (RPS) measures the instantaneous fuel pressure in the delivery pipe. The sensing element (semiconductor element) built in the sensor converts the pressure into a voltage signal, which is used by the PCM to precisely control the injection amount and time. If the actual pressure calculated from the sensor output signal differs from the target rail pressure, it controls the rail pressure by using the rail pressure control valve.