9-3 (9440) L4-2.0L Turbo (2.0 T) (2006)
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Intake Air Temperature Sensor: Description and Operation
Intake Air Sensor (688), T8
Main task
The sensor is a combined pressure and temperature sensor. The sensor measures the current absolute pressure and temperature in the charge air pipe.
Temperature is used to:
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Together with boost pressure determine charge air density. Charge air density is used by air mass control to correct the throttle angle.
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Correct the charge air control valve's PWM ratio. At high temperatures, a higher PWM ratio is required to maintain the same air mass/combustion.
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Correct ignition angle. At low temperatures, earlier ignition is required.
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Blocking of certain diagnostics:
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Blocks certain diagnostics at temperatures below -7 degrees C.
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Reactivates certain diagnostics at temperatures greater than +5 degrees C.
Type
The pressure sensor contains two metal plated ceramic discs mounted in close proximity. The disc located closest to the pressure connection is thinner
and bends when subjected to pressure. The temperature sensor is of NTC type.
Connection
