Charge-Air Temperature Sensor

Charge-Air Temperature Sensor

Charge-air temperature sensor
The charge-air temperature sensor is located on the charge-air pipe between the charge-air cooler and the throttle valve.
The charge-air temperature sensor detects the temperature of the intake air compressed by the turbocharger and cooled by the charge-air cooler.

Functional description
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 (NTC) is installed in the charge-air temperature sensor, whose resistance value drops when the temperature increases. The resistance changes from 76 kOhms to 88 Ohms temperature-dependent, which corresponds to a temperature of -40 °C to 120 °C.







Structure and inner electrical connection
The charge-air temperature sensor is connected via a 2-pin plug connection.
The sensor is supplied with ground by the engine control.







Characteristic curve and setpoint values
The charge air temperature information is transferred to the engine control over a signal line. The charge air temperature is used for the substitute calculation of the air mass. This ensures the plausibility of the value of the hot film air mass meter. In the event of the hot film air mass meter failing, the substitute value is used to determine the fuel quantity and the exhaust-gas recirculation rate.







Please note the following setpoint values for the charge air temperature sensor:

Size Value
Voltage range of charge air 0.3 to 3.3 volts
temperature sensor
Response time Less than 25 s
Intake air temperature resolution ±1 °C
Maximum power consumption 10 mA
Temperature range -40 °C to 120 °C

Diagnosis instructions

Failure of the component
If the charge air temperature sensor fails, the following behavior is to be expected:
- Fault entry in the engine control unit
- Deactivation of charging pressure control
- Exhaust-gas recirculation is deactivated
- Limitation to fuel injection rate (limitation of torque)

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