WOMS
P code powertrain Medium severity

P1112 Intake Air Temperature (IAT) Sensor Circuit Intermittent Low Voltage

The OBD2 code P1112 indicates that the Intake Air Temperature (IAT) sensor circuit is experiencing intermittent low voltage, suggesting a potential issue with the sensor or its wiring that affects its ability to provide...

Definition

The OBD2 code P1112 indicates that the Intake Air Temperature (IAT) sensor circuit is experiencing intermittent low voltage, suggesting a potential issue with the sensor or its wiring that affects its ability to provide accurate temperature readings

Common causes

  • Faulty IAT sensor
  • Damaged wiring or connectors
  • Poor electrical connections
  • Short circuit in the wiring
  • Open circuit in the wiring
  • Corroded terminals
  • Faulty engine control module (ECM)

Common misdiagnoses

  • Faulty IAT sensor
  • Wiring issues or damaged connectors
  • Faulty Engine Control Module (ECM)
  • Vacuum leaks
  • Faulty Mass Air Flow (MAF) sensor
  • Coolant temperature sensor issues
  • Air filter blockage
  • Throttle position sensor problems

Troubleshooting steps

  1. 1. Check the Code and Freeze Frame Data

    Use an OBD-II scanner to confirm the P1112 code is present

  2. 2. Review freeze frame data to understand the conditions under which the code was set (e.g., engine temperature, RPM, vehicle speed)

  3. 3. Visual Inspection

    Inspect the IAT sensor and its wiring harness for any visible damage, such as frayed wires, corrosion, or loose connections

  4. 4. Check the connector for any signs of moisture or dirt that could affect the connection

  5. 5. Test the IAT Sensor

    Disconnect the IAT sensor and measure its resistance with a multimeter. Compare the readings to the manufacturer’s specifications (usually provided in the service manual)

  6. 6. If the resistance is out of spec, the sensor may be faulty and should be replaced

  7. 7. Check the Voltage Supply

    With the ignition on (engine off), check the voltage at the IAT sensor connector. You should see a reference voltage (typically around 5 volts)

  8. 8. If the voltage is low or absent, trace the wiring back to the Engine Control Module (ECM) to identify any breaks or shorts

  9. 9. Inspect Ground Connections

    Ensure that the ground connection for the IAT sensor is secure and free of corrosion. A poor ground can lead to low voltage readings

  10. 10. Check for Short Circuits

    Inspect the wiring for any signs of short circuits to ground or to other circuits. Use a multimeter to check for continuity where it shouldn’t exist

  11. 11. Test the ECM

    If all other components check out, the issue may lie within the ECM itself. This is less common but can happen. Consult a professional if you suspect ECM failure

  12. 12. Clear the Code and Test Drive

    After performing repairs or replacements, clear the code using the OBD-II scanner and take the vehicle for a test drive to see if the code returns

  13. 13. Monitor Live Data

    Use the OBD-II scanner to monitor live data from the IAT sensor while driving. Ensure that the readings are consistent and within the expected range

  14. 14. Consult Technical Service Bulletins (TSBs)

    Check for any TSBs related to the IAT sensor or the specific vehicle model, as there may be known issues or recalls that could apply.Conclusion If you have followed these steps and the issue persists, it may be advisable to consult a professional mechanic or technician for further diagnosis. They may have access to specialized tools and knowledge that can help identify more complex issues