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 10 seconds before conducting the next test.

Procedure for malfunction A

With Consult
1. Turn ignition switch "ON".
2. Select "DATA MONITOR" mode with CONSULT.
3. Wait at least 5 seconds.
4. If 1st trip DTC is detected, go to "DIAGNOSTIC PROCEDURE".

OR

With Generic Scan Tools
1. Turn ignition switch "ON" and wait at least 5 seconds.
2. Select MODE 7 with GST.
3. If 1st trip DTC is detected, go to "DIAGNOSTIC PROCEDURE".

OR

Without Scan Tools
1. Turn ignition switch "ON" and wait at least 5 seconds.
2. Turn ignition switch "OFF", wait at least 10 seconds and then turn "ON".
3. Perform "Diagnostic Test Mode II (Self-diagnostic results)" with ECM.
4. If 1st trip DTC is detected, go to "DIAGNOSTIC PROCEDURE"

Procedure for malfunction B

CAUTION: Always drive vehicle at a sale 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.







With Consult
1. Wait until engine coolant temperature is less than 90 °C (194 °F).
a. Turn ignition switch "ON".
b. Select "DATA MONITOR" mode with CONSULT
c. Check the engine coolant temperature.
d. If the engine coolant temperature is not less than 90 °C (194 °F), turn ignition switch "OFF" and cool down engine.
- Perform the following steps before engine coolant temperature is above 90 °C (194 °F).
2. Turn ignition switch "ON".
3. Select "DATA MONITOR" mode with CONSULT.
4. Start engine.
5. Hold vehicle speed more than 70 KPH (43 MPH) for 105 consecutive seconds.
6. If 1st trip DTC is detected, go to "DIAGNOSTIC PROCEDURE".

OR




With Generic Scan Tools
1. Wait until engine coolant temperature is less than 90 °C (194 °F).
a. Turn ignition switch "ON".
b. Select MODE 1 with GST
c. Check the engine coolant temperature.
d. If the engine coolant temperature is riot less than 90 °C (194 °F), turn ignition switch "OFF" and cool down engine.
- Perform the following steps before engine coolant temperature is above 90 °C (194 °F).
2. Start engine.
3. Hold vehicle speed more than 70 KPH (43 MPH) for 105 consecutive seconds.
4. Select MODE 7 with GST.
5. If 1st trip DTC is detected, go to "DIAGNOSTIC PROCEDURE".

OR




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 KPH (43 MPH) for 105 consecutive seconds.
4. Turn ignition switch "OFF", wait at least 10 seconds and then turn "ON".
5. Perform "Diagnostic Test Mode II (Self-diagnostic results)" with ECM.
6. If 1st trip DTC is detected, go to "DIAGNOSTIC PROCEDURE".







WIRING DIAGRAM




DIAGNOSTIC PROCEDURE










COMPONENT INSPECTION

Check resistance.
If NG, replace intake air temperature sensor.