P0111 Intake Air Temperature Sensor 1 Circuit Range / Performance

COMPONENT LOCATION

GENERAL DESCRIPTION

The Intake Air Temperature Sensor (IATS) is installed into the Mass Air Flow Sensor (MAFS). The IATS uses a thermistor whose resistance changes with the temperature. The electrical resistance of the IATS decreases as the temperature increases, and increases as the temperature decreases. The 5 V power source in the ECM is supplied to the IATS via a resistor in the ECM. That is, the resistor in the ECM and the thermistor in the IATS are connected in series. When the resistance value of the thermistor in IATS changes according to the intake air temperature, the signal voltage also changes. Using this signal, the information of the intake air temperature, the ECM corrects basic fuel injection duration and ignition timing.

DTC DESCRIPTION

ECM monitors temperature difference between MAX. and MIN IATS in order to detect movement in IATS not only Start Test but Drive Test while enable condition is met. If ECM detects intake air temperature changes less than 5.4 °F. ECM determines that a fault exists and a DTC is stored. ECM monitors temperature changes resulting from soaking the vehicle. Therefore, Coolant temperature and Intake temperature should be changed. If ECM detects intake air temperature correlated to coolant temperature does not change ECM determines that a fault exists and a DTC is stored.

DTC DETECTING CONDITION

Item

Detecting Condition

Possible cause

DTC Strategy

Case1

Monitors the difference between the startup coolant and IAT values

1.	Faulty IATS

Case2

Monitors the difference between the startup IAT and coolant values

Case3

Start Test: Monitors the difference between max and min IAT in order to detect movement in IAT for a certain time.

Drive test: Performs the max and min delta check while driving under load for a length of time followed by an idle for a certain time.

Enable Conditions

Case1

Engine soaked time ≥ 360min

Engine running state

No faults present

IAT stored previous trip

Startup Coolant Temperature > -20°C

Airflow > 15 g/s

Vehicle speed > 40kph

Case2

Engine soaked time ≥ 360min

Engine running state

No faults present

IAT stored previous trip

Airflow > 15 g/s

Vehicle speed > 40kph

Case3

Engine soaked time > 360min

Engine Running State

No fault present

IAT stored previous trip

No IAT Tests pending

Threshold value

Case1

Startup Coolant – Startup IAT ≥ 22°C

Case2

Startup IAT – Startup Coolant ≥ 17°C

Case3

Max IAT – Min IAT ≤ 3°C(5.4 °F)

Diagnosis Time

Case1, 2

Continuous (More than 1.25 second failure)

Case3

Continuous (10 min.)

MIL On Condition

NO MIL ON(DTC only)

SPECIFICATION

Temp. (°C)	Resistance (kΩ)	Temp. (°C)	Resistance (kΩ)
-40	40.93 ~ 48.35	20	2.31 ~ 2.57
-20	13.89 ~ 16.03	40	1.08 ~ 1.21
0	5.38 ~ 6.09	60	0.54 ~ 0.66
10	3.48 ~ 3.90	80	0.29 ~ 0.34

DIAGNOSTIC CIRCUIT DIAGRAM

SIGNAL WAVEFORM & DATA

Fig.1) Normal data of IATS & ECTS & EOTS at ig on

Fig.2) Normal data of IATS & ECTS & EOTS after warming up.

Fig.3) Normal waveform of IATS

The output signals of IATS & ECTS change smoothly without any rapid changes. These 2 sensor have almost the same characteristic signal during the early period after start. It means that the temperatures of intake air and engine coolant are depended on the temperature of atmosphere. Meanwhile, During engine warm up the output signal of the ECT will change quicker than the IAT signal. even it may not change almost.

MONITOR GDS DATA

1.	Connect GDS to Data Link Connector(DLC).

IG “ON”.

3.	Select “DTC” button, and then Press “DTC Status” to check DTC’s information from the DTCs menu.

4.	Read “DTC Status” parameter.

Is parameter displayed “Present fault”?

	▶ Go to “Component Inspection” procedure.
	▶ Fault is intermittent caused by ECM memory was not cleared after repair. Erase DTC and drive the vehicle to satisfy the enable condition.

COMPONENT INSPECTION

■ Check IATS resistance

1.	IG “OFF” and disconnect IATS connector.

Measure resistance between signal and ground terminals of IATS connector after checking out the temperature of IATS with GDS (Component Side)

Specification :

Temp. (°C)	Resistance (kΩ)	Temp. (°C)	Resistance (kΩ)
-40	40.93 ~ 48.35	20	2.31 ~ 2.57
-20	13.89 ~ 16.03	40	1.08 ~ 1.21
0	5.38 ~ 6.09	60	0.54 ~ 0.66
10	3.48 ~ 3.90	80	0.29 ~ 0.34

Is the measured resistance within specification ?

	▶ Go to “Verification of Vehicle Repair” procedure.
	▶ Substitute with a known – good IATS and check for proper operation. If the problem is corrected, replace IATS

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