- The intake air temperature change is small, 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.
| Last Modified: 11-27-2007 | 1.6 C | |
| Service Category: Engine/Hybrid System | Section: Engine Control | |
| Model Year: 2008 | Model: LX570 | Doc ID: RM000001WPH01IX |
| Title: 3UR-FE ENGINE CONTROL: SFI SYSTEM: DESCRIPTION (2008 LX570) | ||
|
DTC |
P0111 |
Intake Air Temperature Sensor 1 Circuit Range / Performance |
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, 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 Code |
DTC Detection Condition |
Trouble Area |
|---|---|---|
|
P0111 |
When either condition below is met: |
Mass air flow meter |
MONITOR DESCRIPTION
The ECM performs OBD II monitoring based on the values from the intake air temperature sensor. If there is no change of 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 engine switch is turned off or the engine is started (short soak or long soak).
MONITOR STRATEGY
|
Related DTCs |
P0111: Intake air temperature sensor rationality (After engine stop) P0111: Intake air temperature sensor rationality (After cold engine start) |
|
Required Sensors/Components (Main) |
Intake Air Temperature (IAT) sensor |
|
Required Sensors/Components (Related) |
- |
|
Frequency of Operation |
Once per driving cycle |
|
Duration |
10 seconds or more |
|
MIL Operation |
2 driving cycles |
|
Sequence of Operation |
None |
TYPICAL ENABLING CONDITIONS
All:
|
Monitor runs whenever following DTCs are not stored |
None |
After engine stop:
|
Time after engine start |
10 seconds or more |
|
Battery voltage |
10.5 V or higher |
|
ECT sensor circuit |
OK |
|
MAF sensor circuit |
OK |
|
ECT change since engine stop |
-40°C (-40°F) or higher |
|
ECT before engine stop |
70°C (158°F) or higher |
|
Accumulated MAF amount before engine stop |
2,700 g or more |
|
Key-off duration |
30 minutes |
After cold engine start:
|
Key-off duration |
5 hours |
|
Time after engine start |
10 seconds or more |
|
ECT sensor circuit |
OK |
|
MAF sensor circuit |
OK |
|
ECT |
70°C (158°F) or higher |
|
Accumulated MAF amount |
2,700 g or more |
|
Either of the following conditions 1 or 2 is met: |
- |
|
1. Duration while engine load is low |
120 seconds or more |
|
2. Duration while engine load is high |
10 seconds or more |
TYPICAL MALFUNCTION THRESHOLDS
After engine stop:
|
IAT change |
Below 1°C (2°F) |
After cold engine start:
|
IAT change |
Below 1°C (2°F) |
WIRING DIAGRAM
Refer to DTC P0110
.
INSPECTION PROCEDURE
HINT:
Read freeze frame data using the Techstream. Freeze frame data records the engine condition when malfunctions are detected. 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 engine switch on (IG).
(c) Turn the Techstream on.
(d) Enter the following menus: Powertrain / Engine and ECT / Trouble Codes.
(e) Read DTCs.
Result
|
Result |
Proceed to |
|---|---|
|
P0111 and other DTCs are output |
A |
|
P0111 is output |
B |
HINT:
If any DTCs other than P0111 are output, troubleshoot those DTCs first.
|
|
|