DTC 0401

COMPONENT DESCRIPTION
The intake air temperature sensor is mounted to the air duct, detects intake air temperature and transmits a signal to the ECM. The temperature sensing unit uses a thermistor, which is sensitive to the change in temperature. Electrical resistance of the thermistor decreases in response to the temperature rise.

This sensor is not directly used to control the engine system. It is used only for the on board diagnosis.






ON BOARD DIAGNOSIS LOGIC

DIAGNOSTIC TROUBLE CODE CONFIRMATION PROCEDURE
Perform "Procedure for malfunction A" first. If DTC cannot be confirmed, perform "Procedure for malfunction B".

NOTE: If "DIAGNOSTIC TROUBLE CODE CONFIRMATION PROCEDURE" has been previously conducted, always turn ignition switch "OFF" and wait at least 5 seconds before conducting the next test.


Procedure for malfunction A

Without Scan Tools
(1) Turn ignition switch "ON" and wait at least 5 seconds.
(2) Turn ignition switch "OFF", wait at least 5 seconds and then turn "ON".
(3) Perform "Diagnostic Test Mode II (Self-diagnostic results)" with ECM.



Procedure for malfunction B

CAUTION: Always drive vehicle at a safe speed.

TESTING CONDITION:
This test may be conducted with the drive wheels lifted in the shop or by driving the vehicle. If a road test is expected to be easier, it is unnecessary to lift the vehicle.






Without Scan Tools
(1) Wait until engine coolant temperature is less than 90°C (194°F).
(a) Turn ignition switch "ON".
(b) Check voltage between ECM terminal (59) and ground.

Voltage: More than 1.0 (V)

(c) If the voltage is not more than 1.0 (V), turn ignition switch "OFF" and cool down engine.
- Perform the following steps before the voltage is below 1.0 V.

(2) Start engine.
(3) Hold vehicle speed more than 70 km/h (43 MPH) for 100 consecutive seconds.
(4) Turn ignition switch "OFF", wait at least 5 seconds and then turn "ON".
(5) Perform "Diagnostic Test Mode II (Self-diagnostic results)" with ECM.





DIAGNOSIS PROCEDURE






Electrical Diagrams





Circuit Connectors


COMPONENT INSPECTION
Intake air temperature sensor












Check resistance as shown in the figure.

If NG, replace intake air temperature sensor.