S80 AWD V8-4.4L VIN 85 B8444S (2008)
Overview
The fuel pressure, fuel temperature sensor is combined and consists 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.
The fuel pressure sensor is on the right-hand end of the fuel rail.
The fuel pressure-/fuel temperature sensor can be diagnosed by the engine control module (ECM) and its signals (pressure and temperature) can be read
off.
Fuel pressure sensor
The pressure sensor is a Piezo resistive type resistor, the resistance of which changes with the pressure. Depending on the pressure in the fuel rail, an
analog signal of 0 - 5 V is transmitted to the engine control module (ECM). Low pressure results in low voltage, high pressure gives high voltage.
The engine control module (ECM) then uses this signal to adjust the pressure in the fuel rail using the fuel pump control module. See also: Function,
B8444S See: Description and Operation/Engine Control Module (ECM)/Function
The pressure sensor is supplied with 5 V and grounded in the engine control module (ECM). The pressure sensor transmits a signal indicating the fuel
pressure to the engine control module (ECM) on a separate cable.
Note! The absolute pressure is displayed when using parameter read outs 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 resistance in the sensor changes according to the temperature of the fuel. This provides the engine control module (ECM) with a signal of between 0
- 5 V. 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.
Oil level and oil temperature sensor
The sensor is a combined oil level and oil temperature sensor. The function of the sensor is to provide the engine control module (ECM) with
information about the level and temperature of the engine oil in the oil trough.
The sensor consists of:
