SFI SYSTEM (w/ Electronic Throttle Control System), Diagnostic DTC:P0112, P0113

DTC Code DTC Name
P0112 Intake Air Temperature Circuit Low Input
P0113 Intake Air Temperature Circuit High Input

DESCRIPTION

The Intake Air Temperature (IAT) sensor is built into the manifold absolute pressure sensor, and monitors the intake air temperature. The IAT sensor has a built-in thermistor that varies its resistance depending on the temperature of the intake air. When the air temperature is low, the resistance in the thermistor increases. When the temperature is high, the resistance drops. The variations in resistance are reflected in voltage applied to the ECM terminal (see figure 1).

The IAT sensor is connected to the ECM. The 5 V power source voltage in the ECM is applied to the IAT sensor from terminal THA via resistor R.

Resistor R and the IAT sensor are connected in series. When the resistance value of the IAT sensor changes in accordance with changes in the intake air temperature, the voltage at terminal THA also changes. Based on this signal, the ECM increases the fuel injection volume to improve the driveability during cold engine operation.

A0138H8E01

Tech Tips

When the IAT sensor output is outside the normal range, the ECM determines this as a malfunction.

DTC No. DTC Detecting Condition Trouble Area
P0112 IAT sensor output is less than -47°C (-53°F) for 0.5 seconds (3 trip detection logic)

  • Open or short in intake air temperature sensor circuit

  • Short to power source circuit

  • Intake air temperature sensor (built into manifold absolute pressure sensor)

  • ECM
P0113

IAT sensor output is more than 140°C (284°F) for 0.5 seconds

(3 trip detection logic)

  • Short in intake air temperature sensor circuit

  • Intake air temperature sensor (built into manifold absolute pressure sensor)

  • ECM

Tech Tips


  • DTC P0112 is detected when the engine idles for approximately 5 minutes.

  • DTC P0113 is detected when the ignition switch is in the ON position or the engine is running.

  • When DTC P0112 or P0113 is detected, check the intake air temperature by selecting Powertrain / Engine and ECT / Data List / Intake Air on the intelligent tester.

Temperature Displayed Malfunction
Less than -47°C (-53°F) Open circuit or short +B circuit
More than 140°C (284°F) Short circuit

WIRING DIAGRAM

A0136ZBE01

INSPECTION PROCEDURE

Note

After replace the ECM, perform electronic throttle learning Click here.

Tech Tips

Read freeze frame data using the intelligent tester. The ECM records vehicle and driving condition information as freeze frame data the moment a DTC is stored. When troubleshooting, freeze frame data can help determine if the vehicle was moving or stationary, if the engine was warmed up or not, if the air-fuel ratio was lean or rich, and other data from the time the malfunction occurred.

PROCEDURE


  1. READ VALUE OF INTAKE AIR TEMPERATURE SENSOR


    1. Connect the intelligent tester to the DLC3.

    2. Turn the ignition switch to ON and turn the intelligent tester ON.

    3. Select the following menu items: Powertrain / Engine and ECT / Data List / Intake Air.

    4. Read the value.

      Result
      Temperature Displayed Proceed To
      Less than -47°C (-53°F) A
      More than 140°C (284°F) B
      Same as actual intake air temperature C

      Tech Tips


      • If there is an open circuit, the intelligent tester indicates less than -47°C (-53°F).

      • If there is a short to GND, the intelligent tester indicates more than 140°C (284°F).


    B

    CHECK WIRE HARNESS (CHECK FOR SHORT IN WIRE HARNESS) Click here

    C

    GO TO "CHECK FOR INTERMITTENT PROBLEMS"

    A

  2. CHECK WIRE HARNESS (CHECK FOR OPEN IN WIRE HARNESS)


    1. A0138RKE01

      Confirm good condition at the manifold absolute pressure sensor.

    2. Disconnect the B14 manifold absolute pressure sensor connector.

    3. Connect terminals THA and E2 of the vacuum sensor wire harness side connector.

    4. Connect the intelligent tester to the DLC3.

    5. Turn the ignition switch to ON and turn the intelligent tester ON.

    6. Select the following menu items: Powertrain / Engine and ECT / Data List / Intake Air.

    7. Read the value.

      Standard
      140°C (284°F) or more

    8. Reconnect the manifold absolute pressure sensor connector.


    OK

    REPLACE MANIFOLD ABSOLUTE PRESSURE SENSOR

    NG

  3. CHECK HARNESS AND CONNECTOR (INTAKE AIR TEMPERATURE SENSOR - ECM)


    1. A0138X5E01

      Disconnect the B14 manifold absolute pressure sensor connector.

    2. Disconnect the B25 ECM connector.

    3. Measure the resistance.

      Standard resistance
      Tester Connection Specified Condition
      THA (B14-4) - THA (B25-19) Below 1 Ω
      E2 (B14-2) - E21 (E25-20) Below 1 Ω

    4. Reconnect the manifold absolute pressure sensor connector.

    5. Reconnect the ECM connector.


    NG

    REPAIR OR REPLACE HARNESS AND CONNECTOR

    OK

    REPLACE ECM

  4. CHECK WIRE HARNESS (CHECK FOR SHORT IN WIRE HARNESS)


    1. A0136KSE01

      Disconnect the B14 manifold absolute pressure sensor connector.

    2. Connect the intelligent tester to the DLC3.

    3. Turn the ignition switch to ON and turn the intelligent tester ON.

    4. Select the following menu items: Powertrain / Engine and ECT / Data List / Intake Air.

    5. Read the value.

      Standard
      Less than -47°C (-53°F)

    6. Reconnect the manifold absolute pressure sensor connector.


    OK

    REPLACE MANIFOLD ABSOLUTE PRESSURE SENSOR

    NG

  5. CHECK HARNESS AND CONNECTOR (INTAKE AIR TEMPERATURE SENSOR - ECM)


    1. A0138X5E03

      Disconnect the B14 manifold absolute pressure sensor connector.

    2. Disconnect the B25 ECM connector.

    3. Measure the resistance.

      Standard resistance
      Tester Connection Specified Condition
      THA (B14-4) or THA (B25-19) - body ground 10 kΩ or higher

    4. Reconnect the manifold absolute pressure sensor connector.

    5. Reconnect the ECM connector.


    NG

    REPAIR OR REPLACE HARNESS AND CONNECTOR

    OK

    REPLACE ECM