Air Temperature Sensor ( Ambient / Intake ): Testing and Inspection

AFS, IATS:

The air flow sensor adopts the feature of maintaining a certain temperature of the heater for sensor to make the hot film element detect the air flow and send related signal to the ECM.

The ECM then determines the fuel amount and ignition timing and check the information to apply the fuel and A/C load correction.

The IAT is used to detect the temperature of intake air to support the correction of fuel flow and ignition timing, and the compensation of air temperature for idle control.





Features of IAT output

For the measure feature of the IAT at malfunction, if the coolant temperature is normal, the intake air substitution value is 0°C when the coolant temperature is below 69.75°C while the value is 60°C when the coolant temperature is over 69.75°C.

The substitution value should be 60°C when the engine coolant temperature sensor is failed simultaneously.

Using Voltmeter:

Troubleshooting hints
The MIL is turned ON and DTC (diagnostic trouble code) displayed on Hi-scan under the conditions as below.
1. The manifold pressure indicates 118 mb or less for 0.1 second when the ignition key is turned on.
2. The manifold pressure indicates 118 mb or less when the rate is 1980 rpm or less.
3. The rate is 2400 rpm or above when the manifold pressure indicates 986 mb or above, or the accelerator pedal is released (on deacceleration).