4.
Read "DTC Status" parameter
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.
The purpose of this diagnosis is to detect a stuck intake air temperature signal. The diagnostic function checks whether after a variation of the calculated intake air temperature also a variation of the measured intake air temperature is detected.
ECM sets DTC P0111 when the variation of measured intake air temperature from engine start is smaller than threshold while variation of calculated intake air temperature by ECM is greater than threshold.
Item | Detecting Condition | Possible Cause | |
DTC Strategy | case1) | ● Check intake air temperature signal stuck. | |
case2) | ● Difference between maximun and minimum air temperature | ||
Enable Conditions | ● Time after engine start > 300sec. ● Coolant temp. > 76℃(169℉) ● Coolant temp. increasing after start > 40℃(104℉) ● [Accumulated time for vehicle speed > 70kph(13.5mph)] > 100sec. ● No relevant failure | ||
Threshold value | case1) | ● Variation of Intake Air Temperature after starting <5.25℃ | |
case2) | ● Maximum intake air temp. - minimum intake air temp. < 1.5 at below 30℃(or 3 at below 60℃)) | ||
Diagonostic Time | ● 5 sec. | ||
Mil On Condition | ● 2 Driving Cycles | ||
Temp.(°C) | Temp.(°F) | Resistance(kΩ) | Temp.(°C) | Temp.(°F) | Resistance(kΩ) |
-10 | 14 | 8.5~9.7 | 20 | 68 | 2.3~2.5 |
0 | 32 | 5.4~6.1 | 30 | 86 | 1.6~1.7 |
10 | 50 | 3.5~3.9 | 80 | 176 | Approx. 0.3 |
Fig 1,2) Signal decreases with increasing sensor temperature and increases with decreasing sensor temperature : Approx. 3769mV at 19.5℃(at IG ON), Approx. 3574mV at 24.0℃(at Idle)
Fig 3) Open or short to battery in signal circuit/Open in ground circuit : Approx. 5V
Fig 4) Short to ground in signal circuit : Approx. 0V
Connect scan tool and select "Diagnostic Trouble Codes(DTCs)" mode.
Press F4(DTAL) to select DTC information from the DTCs menu.
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"?
History (Not Present) fault : DTC occurred but has been cleared.
Present fault : DTC is occurring at present time.
 | ▶ Fault is intermittent caused by poor contact in the sensor’s and/or the PCM’s connector, which was repaired but PCM memory was not cleared. Thoroughly check connectors for looseness, poor connection, bending, corrosion, contamination, deterioration, or damage. Repair or replace as necessary and go to "Verification of Vehicle Repair" procedure. |
 | ▶ Go to next step as below. |
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.
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 "Component Inspection" procedure . |
Ignition "OFF"
Disconnect IATS connector.
Measure resistance between terminals 3 and 4 of the sensor connector(Component side).
Temp.(°C) | Temp.(°F) | Resistance(kΩ) | Temp.(°C) | Temp.(°F) | Resistance(kΩ) |
-10 | 14 | 8.5~9.7 | 20 | 68 | 2.3~2.5 |
0 | 32 | 5.4~6.1 | 30 | 86 | 1.6~1.7 |
10 | 50 | 3.5~3.9 | 80 | 176 | Approx. 0.3 |
Is resistance within the specification?
| ▶ Check for poor connection between ECM and component: backed out terminal, improper mating, broken locks or poor terminal to wire connection. Repair as necessary and go to "Verification of Vehicle Repair" procedure. |
| ▶ Check IATS for contamination, deterioration, or damage. Substitute with a known-good IATS and check for proper operation. If the problem is corrected, replace IATS and then 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"?
YES
▶ System performing to specification at this time. Clear the DTC
NO
▶ Go to the applicable troubleshooting procedure.
