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Charge Air Pressure And Temperature Sensor, Basic Function - GF09.41-P-2000A

Engine 139, 176, 177, 254, 256, 260, 264, 274, 279, 608 

Example illustration 

G14472026Courtesy of MERCEDES-BENZ USA

Overview 

This document contains information on:

General 

Via the charge air pressure-and-temperature sensor, the combustion Engine control unit determines the absolute pressure and the charge air temperature in the intake manifold.

The charge air pressure-and-temperature sensor is located in the intake manifold behind the throttle valve actuator.

Function 

Pressure sensor for determining the boost pressure (absolute pressure) 

The intake air in the intake manifold is routed via a bore to a silicon diaphragm with four pressure-dependent resistors and deforms this. The resistors at the silicon diaphragm are located so that the transverse stress of the resistive bridge changes during the deformation of the diaphragm.

The electronic analysis system amplifies this transverse stress and compensates in this way for possible temperature fluctuations or compensates for any manufacturing tolerances of the resistors. It then forwards the measurement voltage filtered in this way to the combustion Engine control unit that based on this derives the absolute pressure in the intake manifold.

Temperature sensor for charge air temperature measurement 

The electrical resistance of the NTC precision resistor varies according to charge air temperature. Electrical resistance decreases as temperature increases.

The resistance variation results in a voltage change that is used by the combustion Engine control unit to calculate the charge air temperature

IMPORTANT NTC resistor: The electrical resistance falls as the temperature increases (NTC thermistor).

  Component descriptions     
  Intake/charge air temperature sensor, component description Engine 176, 279 in model 223 GF07.04-P-6067A
  Intake/charge air pressure and temperature sensor, component description Engine 176, 256 in model 223 GF07.04-P-6069A
  Intake/charge air pressure sensor, component description Engine 279 in model 223 GF07.04-P-6074A