P0111

3UZ-FE ENGINE CONTROL SYSTEM: SFI SYSTEM: P0111: Intake Air Temperature Sensor Gradient Too High
P0111 - Intake Air Temperature Sensor Gradient Too High

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 is low, the resistance of the thermistor increases. When the temperature is 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, the voltage at terminal THA also varies accordingly. Based on this signal, the ECM increases the fuel injection volume when the engine is cold to improve driveability.





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 within the normal range, 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 after the engine is started (short soak or long soak).

MONITOR STRATEGY





TYPICAL ENABLING CONDITIONS

All:





After engine stop:





After cold engine start:





TYPICAL MALFUNCTION THRESHOLDS

After engine stop:





After cold engine start:





CONFIRMATION DRIVING PATTERN





- Connect the Techstream to the DLC3.

- Turn the ignition switch to ON and turn the Techstream on.

- Clear DTCs (even if no DTCs are stored, perform the clear DTC operation).

- Turn the ignition switch off and wait for at least 30 seconds.

- Turn the ignition switch to ON and turn the Techstream on [A].

- Start the engine and warm it up until the ECT reaches 75°C (167°F) or higher [B].

- Idle the engine for 5 minutes or more [C].

HINT
During steps [A] through [C], if the change in the intake air temperature is below 1°C (1.8°F), the intake air temperature sensor (MAF meter) is malfunctioning. It is not necessary to continue this procedure.

- Enter the following menus: Powertrain / Engine / Trouble Codes [D].

- Read the pending DTCs.

HINT
- If a pending DTC is output, the system is malfunctioning.
- If a pending DTC is not output, perform the following procedure.
- Enter the following menus: Powertrain / Engine / Utility / All Readiness.

- Input the DTC: P0111.

- Check the DTC judgment result.





HINT
- If the judgment result shows ABNORMAL, the system has a malfunction.
- If the judgment result shows INCOMPLETE or UNKNOWN, perform steps [E] and [F].
- Drive the vehicle at 40 km/h (25 mph) or more for a total of 5 minutes or more [E].

CAUTION:
When performing the confirmation driving pattern, obey all speed limits and traffic laws.

- Check the DTC judgment result again [F].

HINT
If the judgment result shows INCOMPLETE or UNKNOWN, perform steps [E] and [F] again.

- If no pending DTC is output, perform a universal trip and check for permanent DTCs Reading and Clearing Diagnostic Trouble Codes.

HINT
- If a permanent DTC is output, the system is malfunctioning.
- If no permanent DTC is output, the system is normal.
WIRING DIAGRAM

Refer to DTC P0110 P0110.

INSEPCTION PROCEDURE

PROCEDURE

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

(a) Connect the Techstream to the DLC3.

(b) Turn the ignition switch to ON.

(c) Turn the Techstream on.

(d) Enter the following menus: Powertrain / Engine / Trouble Codes.

(e) Read the DTCs.

Result:





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

B -- REPLACE MASS AIR FLOW METER Service and Repair

A -- GO TO DTC CHART Diagnostic Trouble Code Descriptions