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 PCM is supplied to the IATS via a resistor in the PCM. That is, the resistor in the PCM 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 PCM corrects basic fuel injection duration and ignition timing.
PCM sets DTC P0112 if the PCM detects signal voltage lower than the possible range of a properly operating IATS.
Item | Detecting Condition | Possible Cause |
DTC Strategy | ● Voltage range check. | ● Short to ground in signal harness. ● Contact resistance in connections ● Faulty IAT sensor |
Enable Conditions | ● 6 ＜ Battery voltage ＜ 16V ● After 60 seconds from engine start | |
Threshold value | ● Measured intake air temperature ＞ 142℃(287℉) | |
Diagonostic Time | ● 5 seconds. |
Temp.(°C) | Temp.(°F) | Resistance(kΩ) | Temp.(°C) | Temp.(°F) | Resistance(kΩ) |
-20 | -4 | 14.26 ~ 16.02 | 40 | 104 | 1.11 ~ 1.19 |
0 | 32 | 5.50 ~ 6.05 | 60 | 140 | 0.57 ~ 0.60 |
20 | 68 | 2.35 ~ 2.54 | 80 | 176 | 0.31 ~ 0.32 |
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 "Monitor Scantool Data" procedure
Ignition "ON" & Engine "OFF".
Disconnect IAT sensor connector.
Connect Scantool and monitor the "INT.AIR TEMP. SNSR(V)" parameter on the Scantool data list.
Specification : Approx. 5V
Is displayed IAT data near the specified value.?
▶ Possibility of sensor malfunction. Go to "Component Inspection" procedure.
▶ Possibility of signal circuit short to ground. Go to next step as below.
Ignition "OFF".
Disconnect IATS connector.
Measure resistance between terminal 5 of the sensor harness connector and chassis ground.
Specification : Infinite
Is resistance within the specification?
▶ Go to "Terminal and Connector Inspection" procedure.
▶ Repair short to ground in harness and go to "Verification of Vehicle Repair" procedure.
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 .
Measure resistance between terminals 1 and 5 of the sensor connector(Component side).
Temp.(°C) | Temp.(°F) | Resistance(kΩ) | Temp.(°C) | Temp.(°F) | Resistance(kΩ) |
-20 | -4 | 14.26 ~ 16.02 | 40 | 104 | 1.11 ~ 1.19 |
0 | 32 | 5.50 ~ 6.05 | 60 | 140 | 0.57 ~ 0.60 |
20 | 68 | 2.35 ~ 2.54 | 80 | 176 | 0.31 ~ 0.32 |
Is resistance within the specification?
▶ Check for poor connection between PCM 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"?
▶ System performing to specification at this time. Clear the DTC
▶ Go to the applicable troubleshooting procedure.
