P0111

1NZ-FXE 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 (IAT) sensor, in 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 (included in the hybrid vehicle control ECU) 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 according to changes in the IAT. Based on this signal, the ECM increases the fuel injection volume when the engine is cold to improve driveability.





MONITOR DESCRIPTION

After the warm engine is stopped

The ECM (included in the hybrid vehicle control ECU) monitors the intake air temperature variation in the period from when the engine was warmed up on the previous trip until the next engine start. If the change in engine coolant temperature sensor output is less than the threshold, it is determined that a malfunction has occurred in the intake air temperature sensor. When this is detected, the MIL is illuminated and the DTC is set.

After a cold engine is started

The monitor runs when the engine is started cold after 5 hours or more have elapsed since the engine stopped. If the intake air temperature sensor output variation while the engine is warming up is less than the threshold, it is determined that a malfunction has occurred in the intake air temperature sensor. When this is detected in 2 consecutive driving cycles, the MIL is illuminated and the DTC is set.

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

PROCEDURE

1. CHECK ANY OTHER DTCS OUTPUT (IN ADDITION TO DTC P0111)
(a) Connect Techstream to the DLC3.
(b) Turn the power switch ON (IG).
(c) Turn the tester on.
(d) Select the following menu items: Powertrain / Engine and ECT / Trouble Codes.
(e) Read 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