Toyota 2GR-FE Manual page 306

ES–150
DTC
DESCRIPTION
ES
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 drops, the resistance of the thermistor increases. When the temperature rises,
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.
P0111
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
2GR-FE ENGINE CONTROL SYSTEM – SFI SYSTEM
Intake Air Temperature Sensor Gradient Too
P0111
High
Fig. 1
Resistance
(kΩ)
DTC Detection Condition
1. The intake air temperature rise is large, from the
previous trip warm-up to the following trip. (2 trip
detection logic)
2. When the change in the intake air temperature after
engine start is less than the threshold value.
Acceptable
(°C)
Temperature
(°F)
A067628E20
Mass air flow meter assembly
P0111: Intake air temperature sensor rationality (After engine stop)
P0111: Intake air temperature sensor rationality (After cold engine
start)
Trouble Area