3.
Monitor "IATS" parameter on scantool.
The Intake Air Temperature (IAT) sensor measures the temperature of engine intake air. The Intake Air Temperature (IAT) sensor is a thermistor (a variable resistor that changes along with outside air temperature) in series with a fixed resistor in the ECM. The ECM applies 5V to the IAT sensor. The ECM monitors the voltage across the IAT sensor and converts it into a temperature reading. When the outside air temperature is cold the IAT sensor resistance is high, and when the outside air temperature is warm the IAT sensor resistance is low. Therefore, when the air temperature is cold the ECM will receive a high voltage input, and when the air temperature is warm the ECM will receive a low voltage input. The signal from IAT sensor is used for injection duration correction, ignition timing correction and idle speed correction(Air-density correction).
If measured temperature is higher than the maximum threshold value during 2sec, ECM sets DTC P0112.
(In this case, the input signal voltage is the minimum threshold vaue.)
Item | Detecting Condition | Possible Cause |
DTC Strategy | ● Signal check, low | ● Poor connection ● Short to ground in signal circuit ● IATS |
Enable Conditions | ||
Threshold Value | ● Measured temperature 〉126 ℃ | |
Diagnostic Time | ● 2 sec | |
MIL ON Condition | ● 2 driving cycle |
Temperature [℃] | Resistance [Ω] |
-40 (-40) | 40.93 ~ 48.35 |
-30 (-22) | 23.43 ~ 27.34 |
-20 (-4) | 13.89 ~ 16.03 |
-10 (14) | 8.50 ~ 9.71 |
0 (32) | 5.38 ~ 6.09 |
10 (50) | 3.48 ~ 3.90 |
20 (68) | 2.31 ~ 2.57 |
25 (77) | 1.90 ~ 2.10 |
30 (86) | 1.56 ~ 1.74 |
40 (104) | 1.08 ~ 1.21 |
60 (140) | 0.54 ~ 0.62 |
80 (176) | 0.29 ~ 0.34 |
Connect scantool to DLC(Data Link Cable).
Warm up the engine to normal operating temperature.
Monitor "IATS" parameter on scantool.
Is the "IATS" parameter displayed correctly?
▶ Fault is intermittent caused by poor contact in the sensor’s and/or ECM’s connector or was repaired and ECM memory was not cleared. Thoroughly check connectors for looseness, poorconnection, ending, corrosion, contamination, deterioration, or damage. Repair or replace asnecessary and go to "Verification of Vehicle Repair" procedure.
▶ Go to "Terminal and Connector Inspection" procedure.
Many malfunctions in the electrical system are caused by poor harness and terminals. Faults can also be caused by interference from other electrical systems, and mechanical or chemical damage.
Thoroughly check connectors for looseness, poor connection, bending, corrosion, contamination, deterioration, or damage.
Has a problem been found?
▶ Repair as necessary and go to "Verification of vehicle Repair" procedure.
▶ Go to " Signal Circuit Inspection " procedure.
IG "OFF".
Disconnect IATS connector.
IG "ON" ＆ ENG "OFF".
Measure voltage between terminal 3 of IATS harness connector and chassis ground.
Specification : Approx. 5V
Is the measured voltage within specification?
▶ Go to "Component Inspection" procedure.
▶ Repair or replace as necessary and then, go to "Verification of Vehicle Repair" procedure.
Check IATS resistance.
IG "OFF".
Disconnect IATS connector.
Measure resistance between terminal 3 and 4 of IATS connector(Component Side).
Specification :
Temperature [℃] | Resistance [Ω] |
-40 (-40) | 40.93 ~ 48.35 |
-30 (-22) | 23.43 ~ 27.34 |
-20 (-4) | 13.89 ~ 16.03 |
-10 (14) | 8.50 ~ 9.71 |
0 (32) | 5.38 ~ 6.09 |
10 (50) | 3.48 ~ 3.90 |
20 (68) | 2.31 ~ 2.57 |
25 (77) | 1.90 ~ 2.10 |
30 (86) | 1.56 ~ 1.74 |
40 (104) | 1.08 ~ 1.21 |
60 (140) | 0.54 ~ 0.62 |
80 (176) | 0.29 ~ 0.34 |
Is the measured resistance within specification ?
▶ Many malfunctions in the electrical system are caused by poor harness(es) and terminals. Faults can also be caused by interference from other electrical systems, and mechanical or chemical damage. So, check poor connections and the related circuit between ECM and component thoroughly. Repair as necessary and 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 and go to "Verification of Vehicle Repair" procedure.
After a repair, it is essential to verify that the fault has been corrected.
Connect scan tool and select "Diagnostic Trouble Codes(DTCs)" mode.
Press F4(DTAL) and confirm that "DTC Readiness Flag" indicates "Complete".
If not, drive the vehicle within conditions noted in the freeze frame data or enable conditions.
Read "DTC Status" parameter.
Is parameter displayed "History(Not Present) fault"?
▶ System performing to specification at this time. Clear the DTC.
▶ Go to the applicable troubleshooting procedure.
