SFI SYSTEM(w/o EGR System), Diagnostic DTC:P0112 and P0113

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

DESCRIPTION

A280861E01

The intake air temperature sensor, mounted on the mass air flow meter 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 supply 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.

Tip:

When DTC P0112 or P0113 is stored, 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. The ECM continues operating in fail-safe mode until a pass condition is detected.

DTC No.

Detection Item

DTC Detection Condition

Trouble Area

Warning Indicate

Memory

P0112

Intake Air Temperature Circuit Low Input

Short in the 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 assembly)

  • ECM

Comes on

DTC stored

P0113

Intake Air Temperature Circuit High Input

Open in the 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 assembly)

  • ECM

Comes on

DTC stored

Tip:

When either of these DTCs is stored, check the intake air temperature by entering the following menus: Powertrain / Engine and ECT / All Data / Intake Air.

Temperature Displayed

Malfunction

-40°C (-40°F)

Open circuit

140°C (284°F) or higher

Short circuit

MONITOR DESCRIPTION

The ECM monitors the sensor voltage and uses this value to calculate the intake air temperature. When the sensor output voltage deviates from the normal operating range, the ECM interprets this as a malfunction in the intake air temperature sensor and stores a DTC.

Example:

If the sensor output voltage is higher than 4.91 V for 0.5 seconds or more, the ECM determines that there is an open in the intake air temperature sensor circuit and stores DTC P0113. Conversely, if the output voltage is below 0.18 V for 0.5 seconds or more, the ECM determines that there is a short in the sensor circuit and stores DTC P0112.

If the malfunction is not repaired successfully, a DTC is stored 0.5 seconds after the engine is next started.

CONFIRMATION DRIVING PATTERN

Turn the engine switch on (IG) and wait for 5 seconds or more.

WIRING DIAGRAM

A178643E15

CAUTION / NOTICE / HINT

Tip:

Read freeze frame data using the intelligent tester. Freeze frame data records the engine condition when malfunctions are detected. 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 USING INTELLIGENT TESTER (INTAKE AIR)

    1. Connect the intelligent tester to the DLC3.

    2. Turn the engine switch on (IG).

    3. Turn the tester on.

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

      Powertrain > Engine and ECT > Data List

      Tester Display

      Intake Air

    5. Read the value displayed on the tester.

      OK

      Same as actual intake air temperature

      Result

      Result

      Proceed to

      -40°C (-40°F)

      A

      140°C (284°F) or higher

      B

      Same as actual intake air temperature

      C

      Tip:
      • 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) or higher.

    B

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

    C

    CHECK FOR INTERMITTENT PROBLEMS

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

    1. A127961C02

      *1

      Mass air flow meter assembly

      *2

      ECM

      *a

      Front view of wire harness connector

      (to Mass Air Flow Meter Assembly)

      Disconnect the mass air flow meter assembly connector.

    2. Connect terminals 4 (THA) and 5 (E2) of the mass air flow meter wire harness side connector.

    3. Connect the intelligent tester to the DLC3.

    4. Turn the engine switch on (IG).

    5. Turn the tester on.

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

      Powertrain > Engine and ECT > Data List

      Tester Display

      Intake Air

    7. Read the value displayed on the tester.

      Standard value

      140°C (284°F) or higher

      Result

      Result

      OK

      NG

    OK

    CONFIRM GOOD CONNECTION TO SENSOR. IF OK, REPLACE MASS AIR FLOW METER ASSEMBLY

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

    1. Disconnect the mass air flow meter assembly connector.

    2. Disconnect the ECM connector.

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

      Standard Resistance

      Tester Connection

      Condition

      Specified Condition

      C27-4 (THA) - C29-15 (THA)

      Always

      Below 1 Ω

      C27-5 (E2) - C29-7 (E2)

      Always

      Below 1 Ω

      Result

      Result

      OK

      NG

    OK

    CONFIRM GOOD CONNECTION TO ECM. IF OK, REPLACE ECM

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

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

    1. A186168C13

      *1

      Mass air flow meter assembly

      *2

      ECM

      Disconnect the mass air flow meter assembly connector.

    2. Connect the intelligent tester to the DLC3.

    3. Turn the engine switch on (IG).

    4. Turn the tester on.

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

      Powertrain > Engine and ECT > Data List

      Tester Display

      Intake Air

    6. Read the value displayed on the tester.

      Standard value

      -40°C (-40°F)

      Result

      Result

      OK

      NG

    OK

    REPLACE MASS AIR FLOW METER ASSEMBLY

    NG
  5. CHECK HARNESS AND CONNECTOR (MASS AIR FLOW METER ASSEMBLY - ECM)

    1. Disconnect the mass air flow meter assembly connector.

    2. Disconnect the ECM connector.

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

      Standard Resistance

      Tester Connection

      Condition

      Specified Condition

      C27-4 (THA) or C29-15 (THA) - Body ground

      Always

      10 kΩ or higher

      Result

      Result

      OK

      NG

    OK

    REPLACE ECM

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR