Functional description

Intake-manifold pressure sensor 

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.

Intake-air temperature sensor 

A temperature-dependent electrical resistor is used for temperature sensing. The circuit contains a voltage divider where the resistance can be measured depending on the temperature. A temperature is converted using a characteristic curve specific to the sensor. An NTC resistor is installed in the intake air temperature sensor; its resistance value falls as the temperature rises. The resistance changes from 167 kΩ to 150 Ω depending on temperature, which corresponds to a temperature of -40°C to 130°C.

Fig 1: Identifying Intake Pipe Pressure Sensor, Throttle Actuator, Intake Plenum

Courtesy of BMW OF NORTH AMERICA, INC.