A value from modeling that have been retrieved from an intake air temperature sensor has been currently been in use for outside temperature detection. However, it is difficult to use this value due to the properties of the turbo charger, because the temperature shows a great increase during the charging. Therefore, the outside temperature sensor is installed in front of the radiator to directly measure the outside temperature.
ECM sets DTC P0071 when the variation of measured ambient air temperature from cold(or warm) engine start is out of range in threshold value(refer to Detecting condition).
Item
Detecting Condition
Possible Cause
DTC Strategy
Plausibility check
Faulty AAT
Enable
Conditions
Case1
modeled Temp. AAT < 190.5 °C
change of IAT(between two measurements) <1.5 °C
change of AAT(between two measurements)<1.5 °C
79.5 °C < ECT Temp. < 105.0 °C
Case2
1500rpm < engine speed < 4000rpm
35kg/h <mass air flow < 200kg/h
pressure quotient(PUT/AMP) <1.5
43.5mph < Vehicle speed < 81mph
Failure not detected for DTCs
Case3
Time after start < 180 sec
change of IAT (between two measurements) <1.5 °C
change of AAT (between two measurements) <5.25 °C
engine off time > 450 min
ECT temp.(at engine start) - ECT temp.(at engine stop) > 40 °C
ECT temp. < 34 °C
Threshold Value
measured AAT - modeled AAT <=-15 °C (hot engine)
measured AAT - modeled AAT >= 15 °C (hot engine)
measured AAT - modeled AAT >= 12 °C (cold engine)
Diagnostic Time
immediately
MIL On Condition
2 Driving Cycles
AAT Temp.(?)
Resistance(K?)
-40
55.61 ~ 66.21
-20
-4
18.76 ~ 21.37
0
32
7.62 ~ 7.95
20
68
3.18 ~ 3.37
25
77
2.63 ~ 2.77
40
104
1.50 ~ 1.62
60
140
0.76 ~ 0.84
80
176
0.40 ~ 0.45