Fuel Pressure Sensor / Fuel Temperature Sensor (Only Vehicles With Demand Controlled Fuel Pumps)
The fuel pressure sensor is combined and consisted of both the fuel pressure sensor and the fuel temperature sensor. The sensor detects the fuel pressure (the absolute pressure) and the temperature of the fuel in the fuel rail.
Fuel pressure sensor
The pressure sensor is a Piezo resistive type resistor, the resistance of which changes with the pressure. The signal voltage varies with the pressure in the fuel rail. Low pressure produces low voltage, high pressure produces high voltage.
The engine control module (ECM) compares the signal with its integrated atmospheric pressure sensor. The engine control module (ECM) uses the fuel pump control module to regulate the pressure in the fuel rail. See also: Fuel pressure regulation (only vehicles with demand controlled fuel pumps)
The engine control module (ECM) can diagnose the fuel pressure sensor. Its signals (pressure and temperature) can be read using appropriate diagnostic tool.
The absolute pressure is displayed when using appropriate diagnostics tool parameter readout to read off the fuel pressure. If there is no pressure at the fuel rail, the atmospheric pressure will be displayed.
HINT: The relative pressure (absolute pressure minus atmospheric pressure) is displayed when reading off the fuel pressure via a manometer connected to the fuel rail.
Fuel temperature sensor
The temperature sensor is an NTC sensor. The sensor is supplied with voltage (signal) from and grounded in the engine control module (ECM).
The signal to the engine control module (ECM) varies depending on the fuel temperature. The resistance in the sensor changes with temperature. Low temperature results in high voltage (high resistance). High temperature results in low voltage (low resistance).
The engine control module (ECM) uses the signal to calculate the volume of the fuel.
The fuel pressure sensor is on the left-hand end of the fuel rail.