P CODES (POWERTRAIN) P0100 - P0199 P0112

    If your vehicle's Check Engine Light (CEL) is on and you've scanned it for trouble codes, you may have come across the code P0112. This code indicates that the Engine Control Module (ECM) has detected a low input signal from the Intake Air Temperature (IAT) sensor. In this guide, we'll explore the meaning of code P0112, its symptoms, and how to troubleshoot the issue.

    What does Code P0112 Mean?

    The Intake Air Temperature (IAT) sensor measures the temperature of the air entering the engine. This information is used by the Engine Control Module (ECM) to adjust the air/fuel mixture and ignition timing for optimal engine performance. Code P0112 indicates that the ECM has detected a low input signal from the IAT sensor. This could be caused by a problem with the sensor itself, the wiring, or the ECM.

    Symptoms of Code P0112

    The symptoms of code P0112 can vary depending on the vehicle's make and model, but typically include:

    Illuminated Check Engine Light
    Poor fuel economy
    Rough idling or stalling
    Reduced engine power or acceleration
    How to Troubleshoot Code P0112

    Step 1: Check the IAT sensor wiring

    The first step in troubleshooting code P0112 is to check the wiring between the IAT sensor and the ECM. Look for any signs of damage, such as frayed or broken wires, and ensure that all connections are clean and secure. If the wiring looks good, move on to the next step.

    Step 2: Test the IAT sensor

    To test the IAT sensor, use a multimeter to measure its resistance at different temperatures. Refer to your vehicle's service manual for the correct values. If the readings are out of range, the sensor may be faulty and will need to be replaced.

    Step 3: Check the ECM

    If the IAT sensor and wiring are both in good condition, the problem may be with the ECM itself. To test this, you'll need a diagnostic tool that can communicate with the ECM. Use the tool to check for any fault codes related to the IAT sensor or temperature sensor circuit. If no fault codes are present, try resetting the ECM and see if the code returns.

    Step 4: Replace the IAT sensor

    If the IAT sensor is found to be faulty, it will need to be replaced. Refer to your vehicle's service manual for the correct procedure. Once the new sensor is installed, clear any fault codes and test drive the vehicle to ensure that the CEL does not illuminate again.

    Step 5: Replace the ECM

    If the ECM is found to be faulty, it will need to be replaced. This is a more complicated and expensive repair, so it's important to ensure that the ECM is the actual cause of the problem before replacing it.


    Code P0112 is an indication of a problem with the Intake Air Temperature (IAT) sensor circuit. The symptoms of this code include poor fuel economy, rough idling, and reduced engine power. To troubleshoot this code, start by checking the IAT sensor wiring and testing the sensor itself. If both are in good condition, check the ECM for any fault codes or reset it to see if the code returns. If the sensor is faulty, replace it, and if the ECM is faulty, replace it as a last resort. By following these steps, you should be able to resolve the issue and get your vehicle running smoothly again.

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