P0111

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

DTC P0111 - Intake Air Temperature Sensor Gradient Too High

DESCRIPTION





The intake air temperature sensor, in the mass air flow meter, monitors the intake air temperature. The intake air temperature sensor has a built-in thermistor with a resistance that varies according to the temperature of the intake air. When the intake air temperature 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 (included in the hybrid vehicle control ECU) as voltage changes (See Fig. 1).
The intake air temperature sensor is powered by a 5 V supply from the THA terminal of the ECM, via resistor R.
Resistor R and the intake air temperature sensor are connected in series. When the resistance value of the intake air temperature sensor changes, the voltage at terminal THA also varies according to changes in the intake air temperature. Based on this signal, the ECM increases the fuel injection volume when the engine is cold to improve driveability.





MONITOR DESCRIPTION

The ECM (included in the hybrid vehicle control ECU) performs OBD II monitoring based on the values from the intake air temperature sensor. If the change in the sensor value is not 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 power switch is turned off or 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:





WIRING DIAGRAM






INSPECTION PROCEDURE
HINT: Read freeze frame data using the Techstream. The ECM (included in the hybrid vehicle control ECU) records vehicle and driving condition information as freeze frame data the moment a DTC is stored. When troubleshooting, freeze frame data can help determine if the vehicle was moving or stationary, if the engine was warmed up or not, if the air-fuel ratio was lean or rich, and other data from the time the malfunction occurred.

PROCEDURE

1. CHECK ANY OTHER DTCS OUTPUT (IN ADDITION TO DTC P0111)
(a) Connect the Techstream to the DLC3.
(b) Turn the power switch on (IG).
(c) Turn the Techstream on.
(d) Enter the following menus: Powertrain / Engine and ECT / 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
A -- GO TO DTC CHART Diagnostic Trouble Code Descriptions