Nissan Altima 2007-2012 Service Manual: P0127 IAT Sensor

Description

The intake air temperature sensor is built-into mass air flow sensor (1). The sensor 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.

<Reference data>

*: These data are reference values and are measured between ECM terminal 50 (Intake air temperature sensor) and ground.

CAUTION: Do not use ECM ground terminals when measuring input/output voltage. Doing so may result in damage to the ECM's transistor. Use a ground other than ECM terminals, such as the ground.

DTC Logic

DTC DETECTION LOGIC

DTC CONFIRMATION PROCEDURE

1.PRECONDITIONING

If DTC Confirmation Procedure has been previously conducted, always turn ignition switch OFF and wait at least 10 seconds before conducting the next test.

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.

>> GO TO 2.

2.PERFORM DTC CONFIRMATION PROCEDURE

1. Wait until engine coolant temperature is less than 96°C (205°F) - Turn ignition switch ON.

- Select “DATA MONITOR” mode with CONSULT-III.

- Check the engine coolant temperature.

- If the engine coolant temperature is not less than 96°C (205°F), turn ignition switch OFF and cool down engine.

NOTE: Perform the following steps before engine coolant temperature is above 96°C (205°F).

2. Turn ignition switch ON.

3. Select “DATA MONITOR” mode with CONSULT-III.

4. Start engine.

5. Hold vehicle speed at more than 70 km/h (43 MPH) for 95 consecutive seconds.

CAUTION: Always drive vehicle at a safe speed.

6. Check 1st trip DTC.

Follow the procedure “With CONSULT-III” above.

Is 1st trip DTC detected? YES >> Go to EC-721, "Diagnosis Procedure".

NO >> INSPECTION END

Diagnosis Procedure

1.CHECK GROUND CONNECTION

1. Turn ignition switch OFF.

2. Check ground connection E9. Refer to Ground Inspection in GI-45, "Circuit Inspection".

Is the inspection result normal? YES >> GO TO 2.

NO >> Repair or replace ground connection.

2.CHECK INTAKE AIR TEMPERATURE SENSOR

Refer to EC-721, "Component Inspection".

Is the inspection result normal? YES >> GO TO 3.

NO >> Replace mass air flow sensor (with intake air temperature sensor).

3.CHECK INTERMITTENT INCIDENT

Refer to GI-42, "Intermittent Incident".

>> INSPECTION END

Component Inspection

1.CHECK INTAKE AIR TEMPERATURE SENSOR

1. Turn ignition switch OFF.

2. Disconnect mass air flow sensor harness connector.

3. Check resistance between mass air flow sensor terminals as follows.

Is the inspection result normal? YES >> INSPECTION END

NO >> Replace mass air flow sensor (with intake air temperature sensor).

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