Intake air temperature sensor: Notes
The pressure sensor is combined with a temperature sensor and measures the current absolute pressure and temperature in the charge air pipe.
The temperature sensor (407) is positioned in the intake manifold in front of the throttle and is of NTC type. The control module measures the air temperature in the intake manifold by feeding the sensor 5 V through a 2.74 kohm resistor in the control module from pin 15. The sensor is grounded from pin 70. The voltage across the resistor in the control module is proportional to the intake air temperature.
The pressure sensor and temperature sensor functions (603) are integrated in the same component.
The temperature is used to:
- Determine the density of the charge air together with charge air pressure. The charge air density is used by the air mass control to correct the throttle angle.
- Correct the PWM ratio of the charge air control valve. A higher PWM ratio is required at high temperatures to obtain the same air mass/combustion.
- Correct the ignition timing. A more advanced ignition is required at low temperatures.
- Block OBD II diagnostics at temperatures below -7°C.