SFI SYSTEM (w/o Secondary Air Injection System), Diagnostic DTC:P0100/31, P0102/31, P0103/31

DTC Code DTC Name
P0100/31 Mass or Volume Air Flow Circuit
P0102/31 Mass or Volume Air Flow Circuit Low Input
P0103/31 Mass or Volume Air Flow Circuit High Input

DESCRIPTION

The Mass Air Flow (MAF) meter is a sensor that measures the amount of air flowing through the throttle valve. The ECM uses this information to determine the fuel injection time and to provide appropriate air-fuel ratio. Inside the MAF meter, there is a heated platinum wire which is exposed to the flow of intake air.

By applying a specific electrical current to the wire, the ECM heats it to a given temperature. The flow of incoming air cools both the wire and an internal thermistor, affecting their resistance. To maintain a constant current value, the ECM varies the voltage applied to these components in the MAF meter. The voltage level is proportional to the airflow through the sensor, and the ECM uses it to calculate the intake air volume.

The circuit is constructed so that the platinum hot wire and the temperature sensor provide a bridge circuit, and the power transistor is controlled so that the potentials of A and B remain equal to maintain the predetermined temperature.

Tech Tips

When any of these DTCs are set, the ECM enters fail-safe mode. During fail-safe mode, the ignition timing is calculated by the ECM, according to the engine RPM and throttle valve position. Fail-safe mode continues until a pass condition is detected.

A01BDZ0E01
DTC No. DTC Detection Conditions Trouble Areas
P0100/31 Mass Air Flow (MAF) meter voltage less than 0.2 V, or more than 4.9 V for 3 seconds

  • Open or short in MAF meter circuit

  • MAF meter

  • ECM
P0102/31 Mass Air Flow (MAF) meter voltage less than 0.2 V, for 3 seconds

  • Open or short in MAF meter circuit

  • MAF meter

  • ECM
P0103/31 Mass Air Flow (MAF) meter more than 4.9 V for 3 seconds

  • Open or short in MAF meter circuit

  • MAF meter

  • ECM

Tech Tips

When any of these DTCs are set, check the air-flow rate by selecting the following menu items on an intelligent tester: Powertrain / Engine and ECT / Data List / MAF.

Mass Air Flow Rate (g/s) Malfunctions
Approximately 0.0

  • Open in Mass Air Flow (MAF) meter power source circuit

  • Open or short in VG circuit
271.0 or more

  • Open in EVG circuit

MONITOR DESCRIPTION

If there is a defect in the MAF meter or an open or short circuit, the voltage level deviates from the normal operating range. The ECM interprets this deviation as a malfunction in the MAF meter and sets a DTC.

Example:

When the sensor voltage output remains less than 0.2 V, or more than 4.9 V, for more than 3 seconds, the ECM sets a DTC.

If the malfunction is not repaired successfully, a DTC is set 3 seconds after the engine is next started.

WIRING DIAGRAM

A01BEW6E01

INSPECTION PROCEDURE

Tech Tips

Read freeze frame data using an 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 (MASS AIR FLOW RATE)


    1. Connect an intelligent tester to the DLC3.

    2. Start the engine.

    3. Turn the tester ON.

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

    5. Read the values displayed on the tester.

      Result
      Mass Air Flow Rate (g/s) Proceed To
      0.0 A
      271.0 or more B
      Between 1.0 and 270.0 (*1) C

      *1: The value must be changed when the throttle valve is open or closed.


    B

    INSPECT ECM (SENSOR GROUND) Click here

    C

    CHECK FOR INTERMITTENT PROBLEMS

    A

  2. INSPECT MASS AIR FLOW METER (POWER SOURCE VOLTAGE)


    1. A01BDIZE23

      Disconnect the A3 Mass Air Flow (MAF) meter connector.

    2. Turn the ignition switch to the ON position.

    3. Measure the voltage between the terminal of the wire harness side connector and body ground.

      Voltage
      Tester Connections Specified Conditions
      +B (A3-1) - Body ground 9 to 14 V

    4. Reconnect the MAF meter connector.


    NG

    CHECK HARNESS AND CONNECTOR (MASS AIR FLOW METER - INTEGRATION RELAY) Click here

    OK

  3. INSPECT ECM (VG VOLTAGE)


    1. A01BDNSE23

      Start the engine.

    2. Measure the voltage between the terminals of the ECM connector.

      Tech Tips

      The transmission gear selector lever should be in the P or N position (A/T vehicle), neutral position (M/T vehicle) and the A/C switch should be turned OFF.

      Voltage
      Tester Connections Conditions Specified Conditions

      VG (D3-28) -

      E2G (D3-30)

      		 Engine idling 0.5 to 3.0 V

    NG

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

    OK

    REPLACE ECM

  4. CHECK HARNESS AND CONNECTOR (MASS AIR FLOW METER - ECM)


    1. A01BEF5E01

      Disconnect the A3 MAF meter connector.

    2. Disconnect the D3 ECM connector.

    3. Measure the resistance.

      Resistance (Check for open)
      Tester Connections Specified Conditions
      VG (A3-3) - VG (D3-28) Below 1 Ω
      E2G (A3-2) - E2G (D3-30) Below 1 Ω
      Resistance (Check for short)
      Tester Connections Specified Conditions
      VG (A3-3) or VG (D3-28) - Body ground 10 kΩ or higher

    4. Reconnect the MAF meter connector.

    5. Reconnect the ECM connector.


    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

    REPLACE MASS AIR FLOW METER

  5. CHECK HARNESS AND CONNECTOR (MASS AIR FLOW METER - INTEGRATION RELAY)


    1. Remove the integration relay (MAIN relay) from the engine room R/B No.1.

    2. A01BGX0E01

      Disconnect the A3 MAF meter connector.

    3. Measure the resistance.

      Resistance (Check for open)
      Tester Connections Specified Conditions
      +B (A3-1) - integration relay (B4) Below 1 Ω
      Resistance (Check for short)
      Tester Connections Specified Conditions

      +B (A3-1) or integration relay (B4)

      - Body ground

      		 10 kΩ or higher

    4. Reconnect the MAF meter connector.

    5. Reinstall the integration relay (MAIN relay).


    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

    INSPECT ECM POWER SOURCE CIRCUIT

  6. INSPECT ECM (SENSOR GROUND)


    1. A01BDNSE24

      Measure the resistance.

      Resistance
      Tester Connections Specified Conditions
      E2G (D3-30) - Body ground Below 1 Ω

    NG

    REPLACE ECM

    OK

  7. CHECK HARNESS AND CONNECTOR (MASS AIR FLOW METER - ECM)


    1. A01BEF5E01

      Disconnect the A3 MAF meter connector.

    2. Disconnect the D3 ECM connector.

    3. Measure the resistance.

      Resistance (Check for open)
      Tester Connections Specified Conditions
      VG (A3-3) - VG (D3-28) Below 1 Ω
      E2G (A3-2) - E2G (D3-30) Below 1 Ω
      Resistance (Check for short)
      Tester Connections Specified Conditions
      VG (A3-3) or VG (D3-28) - Body ground 10 kΩ or higher

    4. Reconnect the MAF meter connector.

    5. Reconnect the ECM connector.


    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

    REPLACE MASS AIR FLOW METER