Turbo Boost Sensor: Description and Operation

Charging Pressure Sensor

Charging pressure sensor
The charging pressure sensor is bolted to the charge air cooler.
This sensor sends the charge air pressure (absolute) before the throttle valve to the engine control.
The purpose of the charging pressure sensor is charging pressure control. The engine control unit also uses the signal of the intake-manifold pressure sensor to calibrate the position of the throttle valve.

Functional description
Strain gauge are used for detecting the pressure. A steel membrane equipped with strain gauge in the sensor is deformed by the adjacent pressure. The changes in resistance in the strain gauge are electronically detected by a Wheatstone bridge and evaluated. The measured voltage is then included as an actual value in the charge-air-pressure control.







Structure and inner electrical connection
The charging pressure sensor is connected by means of a 4-pin plug connection.
The sensor is supplied with 5 Volts by the engine control.







Characteristic curve and setpoint values
The charging pressure information is sent to the engine control across a signal line. The signal for evaluation of the charging pressure fluctuates depending on the pressure. The measuring range of approx. 0.5 to 4.5 Volts corresponds to a charge-air pressure of 20 kPa (0.2 bar) to 250 kPa (2.5 bar).







Observe the following setpoint values for the charging pressure sensor:

Size Value
Voltage range for charge-air 0.5 to 4.5 volts
pressure sensor
Measuring range for charging 0.2 to 2.5 bar
pressure
Maximum output current 10 mA
Temperature range -40 °C to 130 °C

Diagnosis instructions

Failure of the component
If the charge-air pressure sensor fails, the following Behavior is to be expected:
- Fault entry in the engine control unit
- Emergency operation with substitute value

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