SFI 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 sensor, mounted on the mass air flow meter sub-assembly, monitors the intake air temperature. The intake air temperature sensor has a built-in thermistor with a resistance that varies according to the temperature of the intake air. When the intake air temperature is low, the resistance of the thermistor increases. When the temperature is high, the resistance drops. These variations in resistance are transmitted to the ECM as voltage changes (see Fig. 1).

The intake air temperature sensor is powered by a 5 V applied from the THA terminal of the ECM, via resistor R.

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

A017E03E03

Tech Tips

When any of DTCs P0112 and P0113 are set, the ECM enters fail-safe mode. During fail-safe mode, the intake air temperature is estimated to be 20°C (68°F) by the ECM. Fail-safe mode continues until a pass condition is detected.

DTC No. DTC Detection Condition Trouble Area
P0112 Short in intake air temperature sensor circuit for 0.5 seconds (1 trip detection logic)

  • Short in intake air temperature sensor circuit

  • Intake air temperature sensor (built into mass air flow meter sub-assembly)

  • ECM
P0113 Open in intake air temperature sensor circuit for 0.5 seconds (1 trip detection logic)

  • Open in intake air temperature sensor circuit

  • Intake air temperature sensor (built into mass air flow meter sub-assembly)

  • ECM

Tech Tips

When any of these DTCs are set, check the intake air temperature by entering the following menus: Powertrain / Engine and ECT / Data List / All Data / Intake Air.

Temperature Displayed Malfunctions
-40°C (-40°F) Open circuit
140°C (284°F) Short circuit

WIRING DIAGRAM

A017ELHE11

INSPECTION PROCEDURE

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 be helpful in determining whether the vehicle was running or stopped, whether the engine was warmed up or not, whether the air fuel ratio was lean or rich, as well as other data recorded at the time of a malfunction.

PROCEDURE


  1. READ VALUE USING INTELLIGENT TESTER (INTAKE AIR TEMPERATURE)


    1. Connect the intelligent tester to the DLC3.

    2. Turn the ignition switch on (IG).

    3. Turn the tester on.

    4. Enter the following menus: Powertrain / Engine and ECT / Data List / Intake Air.

    5. Read the value displayed on the tester.

      Standard
      Same as actual intake air temperature.
      Result
      Temperature Displayed Proceed to
      -40°C (-40°F) A
      140°C (284°F) B
      Same as actual intake air temperature C

      Tech Tips


      • If there is an open circuit, the intelligent tester indicates -40°C (-40°F).

      • If there is a short circuit, the intelligent tester indicates 140°C (284°F).


    B

    READ VALUE USING INTELLIGENT TESTER (CHECK FOR SHORT IN WIRE HARNESS) Click here

    C

    CHECK FOR INTERMITTENT PROBLEMS Click here

    A

  2. READ VALUE USING INTELLIGENT TESTER (CHECK FOR OPEN IN WIRE HARNESS)


    1. A017EYZE13
      Text in Illustration
      *1 Mass Air Flow Meter Sub-assembly
      *2 ECM
      *a

      Front view of wire harness connector

      (to Mass Air Flow Meter Sub-assembly)

      Disconnect the mass air flow meter sub-assembly connector.

    2. Connect terminals THA and ETHA of the mass air flow meter sub-assembly wire harness side connector.

    3. Connect the intelligent tester to the DLC3.

    4. Turn the ignition switch on (IG).

    5. Turn the tester on.

    6. Enter the following menus: Powertrain / Engine and ECT / Data List / Intake Air.

    7. Read the value displayed on the tester.

      Standard
      140°C (284°F)

    8. Reconnect the mass air flow meter sub-assembly connector.


    NG

    CHECK HARNESS AND CONNECTOR (MASS AIR FLOW METER SUB-ASSEMBLY - ECM) Click here

    OK

    REPLACE MASS AIR FLOW METER SUB-ASSEMBLY Click here

  3. CHECK HARNESS AND CONNECTOR (MASS AIR FLOW METER SUB-ASSEMBLY - ECM)


    1. Disconnect the mass air flow meter sub-assembly connector.

    2. Disconnect the ECM connector.

    3. Measure the resistance according to the value(s) in the table below.

      Standard resistance
      Check for open
      Tester Connection Condition Specified Condition
      B49-15 (THA) - B10-1 (THA) Always Below 1 Ω
      B49-7 (ETHA) - B10-2 (E2) Always Below 1 Ω
      Check for short
      Tester Connection Condition Specified Condition
      B49-15 (THA) or B10-1 (THA) - Body ground Always 10 kΩ or higher
      B49-7 (ETHA) or B10-2 (E2) - Body ground Always 10 kΩ or higher

    4. Reconnect the mass air flow meter sub-assembly connector.

    5. Reconnect the ECM connector.


    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR (MASS AIR FLOW METER SUB-ASSEMBLY - ECM)

    OK

    REPLACE ECM Click here

  4. READ VALUE USING INTELLIGENT TESTER (CHECK FOR SHORT IN WIRE HARNESS)


    1. A017FBEE10
      Text in Illustration
      *1 Mass Air Flow Meter Sub-assembly
      *2 ECM

      Disconnect the mass air flow meter sub-assembly connector.

    2. Connect the intelligent tester to the DLC3.

    3. Turn the ignition switch on (IG).

    4. Turn the tester on.

    5. Enter the following menus: Powertrain / Engine and ECT / Data List / Intake Air.

    6. Read the value displayed on the tester.

      Standard
      -40°C (-40°F)

    7. Reconnect the mass air flow meter sub-assembly connector.


    NG

    READ VALUE USING INTELLIGENT TESTER (CHECK FOR SHORT IN ECM) Click here

    OK

    REPLACE MASS AIR FLOW METER SUB-ASSEMBLY Click here

  5. READ VALUE USING INTELLIGENT TESTER (CHECK FOR SHORT IN ECM)


    1. Disconnect the mass air flow meter sub-assembly connector.

    2. Disconnect the ECM connector.

    3. Connect the intelligent tester to the DLC3.

    4. Turn the ignition switch on (IG).

    5. Turn the tester on.

    6. Enter the following menus: Powertrain / Engine and ECT / Data List / Intake Air.

    7. Read the value displayed on the tester.

      Standard
      -40°C (-40°F)

    8. Reconnect the mass air flow meter sub-assembly connector.

    9. Reconnect the ECM connector.


    NG

    REPLACE ECM Click here

    OK

    REPAIR OR REPLACE HARNESS OR CONNECTOR (MASS AIR FLOW METER SUB-ASSEMBLY - ECM)