Toyota Sienna Service Manual: Intake Air Temperature Sensor Gradient Too High

Toyota Sienna Service Manual / 2GR-FE Engine control system / SFI system / Diagnostic trouble code chart / Intake Air Temperature Sensor Gradient Too High

DTC P0111 Intake Air Temperature Sensor Gradient Too High

DESCRIPTION

DESCRIPTION

The Intake Air Temperature (IAT) sensor, mounted on the Mass Air Flow (MAF) meter, monitors the IAT.

The IAT sensor has a built-in thermistor with a resistance that varies according to the temperature of the intake air. When the IAT becomes low, the resistance of the thermistor increases. When the temperature becomes high, the resistance drops. These variations in resistance are transmitted to the ECM as voltage changes (see Fig. 1).

The IAT sensor is powered by a 5 V supply from the THA terminal of the ECM, via resistor R.

Resistor R and the IAT sensor are connected in series. When the resistance value of the IAT sensor changes according to changes in the IAT, the voltage at terminal THA also varies. Based on this signal, the ECM increases the fuel injection volume when the engine is cold to improve driveability.

DTC No.	DTC Detection Condition	Trouble Area
P0111	The intake air temperature rise becomes larger, from the previous trip warm-up to the following trip.(2 trip detection logic) When the change in the intake air temperature after engine start is less than the threshold value.	Mass air flow meter assembly

MONITOR DESCRIPTION

The ECM performs OBD II monitoring based on the values from the intake air temperature sensor. If there is no change in the sensor value, the ECM will not be able to perform OBD II monitoring or will misdiagnose that there is a malfunction in the sensor. The ECM detects the stuck intake air temperature sensor value by performing monitoring after the ignition switch is turned off or the ignition is started (short soak or long soak).

MONITOR STRATEGY

MONITOR STRATEGY

TYPICAL ENABLING CONDITIONS

All:

TYPICAL ENABLING CONDITIONS

After engine stop:

TYPICAL ENABLING CONDITIONS

After cold engine start:

TYPICAL ENABLING CONDITIONS

TYPICAL MALFUNCTION THRESHOLDS

After engine stop:

TYPICAL MALFUNCTION THRESHOLDS

After cold engine start:

TYPICAL MALFUNCTION THRESHOLDS

WIRING DIAGRAM

Refer to DTC P0110.

INSPECTION PROCEDURE

1 CHECK ANY OTHER DTCS OUTPUT (IN ADDITION TO DTC P0111)

Connect the intelligent tester to the DLC3.
Turn the ignition switch to the ON position.
Turn the tester on.
Enter the following menus: DIAGNOSIS / ENHANCED OBD II / DTC INFO / CURRENT CODES.
Read the DTCs.

Result

Result

HINT: If any DTCs other than P0111 are output, troubleshoot those DTCs first.

GO TO DTC CHART

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