P0112
DTC P0112 INTAKE AIR TEMPERATURE SENSOR1 CIRCUIT LOW INPUTComponent Location:
COMPONENT LOCATION
GENERAL DESCRIPTION
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 PCM. The PCM applies 5 volts to the IAT sensor. The PCM 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 PCM will receive a high voltage input, and when the air temperature is warm the PCM will receive a low voltage input. The signal from IAT sensor is used for injection time correction (Cold post start correction), ignition angle correction(Air temperature correction) and idle speed correction(Air-density correction).
DTC DESCRIPTION
If the value of IAT sensor is lower than threshold, the PCM determines that a fault exists and a DTC is stored.
DTC Detecting Condition:
Schematic Diagram:
Signal Waveform & Data:
MONITOR SCANTOOL DATA
1. Ignition "OFF" & Engine "OFF"
2. Install Scantool and Ignition "ON" & Engine "ON"
3. Monitor Intake Air Temperature Sensor parameter on Current data
Specification: (Error range is 2 - 3%)
4. Is Current data displayed correctly?
YES: Fault is intermittent caused by poor contact in the sensor's and/or PCM's connector or was repaired and 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.
NO: Go to "W/Harness Inspection" procedure.
TERMINAL & CONNECTOR INSPECTION
1. 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.
2. Thoroughly check connectors for looseness, poor connection, bending, corrosion, contamination, deterioration, or damage.
3. Has a problem been found?
YES: Repair as necessary and go to "Verification of Vehicle Repair" procedure.
NO: Go to Signal Circuit Inspection procedure.
SIGNAL CIRCUIT INSPECTION
1. Check reference voltage in harness
1. Ignition "OFF"
2. Disconnect IAT sensor connector.
3. Ignition "ON" & Engine "OFF"
4. Measure voltage between terminal 5 of IAT sensor harness connector and chassis ground.
Specification Approx. 5 V
5. Is the measured voltage within specifications?
YES: Go to "Component Inspection procedure".
NO: Go to "Check for short to ground in harness" as below.
2. Check for short to ground in harness
1. Ignition "OFF"
2. Disconnect IAT sensor connector.
3. Measure resistance between terminal 5 of IAT sensor harness connector and chassis ground.
Specification: Infinite
4. Is the measured resistance within specifications?
YES: Go to "Component Inspection" procedure.
NO:
- Check for short to ground in signal harness.
- Repair or replace as necessary. And then, go to "Verification of Vehicle Repair" procedure.
COMPONENT INSPECTION
1. Check IATS
1. Ignition "OFF"
2. Disconnect IATS connector.
3. Measure resistance between terminal 5 and 3 of IAT connector (Component side).
4. Is the measured resistance within specifications?
YES: Go to "Check PCM" as below.
NO:
- 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.
2. Check PCM
1. Ignition "OFF" & Engine "OFF"
2. Connect Scantool and Ignition "ON"
3. Select simulation function on scantool.
4. Simulate voltage at terminal 5 of IAT sensor signal connector.
5. Does the signal value of IAT sensor changes according to simulation voltage?
YES: 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.
NO: Substitute with a known - good PCM and check for proper operation.
If the problem is corrected, replace PCM and go to "Verification of Vehicle Repair" procedure.
VERIFICATION OF VEHICLE REPAIR
After a repair, it is essential to verify that the fault has been corrected.
1. Monitor and record the Freeze Frame Data for the Diagnostic Trouble Code(DTC) which has been diagnosed.
2. Using a Scantool, Clear the DTCs.
3. Operate the vehicle within conditions noted in the freeze frame data or enable conditions.
4. Monitor that all readiness tests have been verified as Complete
5. Are any DTCs present?
YES: Go to the applicable troubleshooting procedure.
NO: System is performing to specification at this time.