SFI SYSTEM, Diagnostic DTC:P0102 and P0103

DTC Code DTC Name
P0102 Mass Air Flow Circuit Low
P0103 Mass Air Flow Circuit High

DESCRIPTION

The mass air flow meter sub-assembly 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 the appropriate air fuel ratio.

Inside the mass air flow meter sub-assembly, 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 the wire and internal thermistor. 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 create a bridge circuit, and the power transistor is controlled so that the potentials of A and B remain equal to maintain the predetermined temperature.

Tip:

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

A202104E03

DTC No.

Detection Item

DTC Detection Condition

Trouble Area

MIL

Memory

P0102

Mass Air Flow Circuit Low

The mass air flow meter sub-assembly voltage is below 0.2 V for 3 seconds (1 trip detection logic).

  • Open or short in mass air flow meter sub-assembly circuit

  • Mass air flow meter sub-assembly

  • ECM

Comes on

DTC stored

P0103

Mass Air Flow Circuit High

The mass air flow meter sub-assembly voltage is higher than 4.9 V for 3 seconds (1 trip detection logic).

  • Open or short in mass air flow meter sub-assembly circuit

  • Mass air flow meter sub-assembly

  • ECM

Comes on

DTC stored

Tip:

When any of these DTCs are output, check the air flow rate using the GTS. Enter the following menus: Powertrain / Engine and ECT / Data List / All Data / MAF.

Mass Air Flow Rate (gm/sec)

Malfunction

Approximately 0.0

  • Open in mass air flow meter sub-assembly power source circuit

  • Open or short in VG circuit

160.0 or more

  • Open in E2G circuit

MONITOR DESCRIPTION

If there is a defect or an open or short circuit in the mass air flow meter sub-assembly, the voltage level deviates from the normal operating range. The ECM interprets this deviation as a malfunction in the mass air flow meter sub-assembly circuit and stores a DTC.

Example:

When the sensor output voltage remains below 0.2 V, or higher than 4.9 V for 3 seconds, the ECM stores a DTC.

CONFIRMATION DRIVING PATTERN

  1. Connect the GTS to the DLC3.

  2. Turn the ignition switch to ON and turn the GTS on.

  3. Clear the DTCs (even if no DTCs are stored, perform the clear DTC procedure).

  4. Turn the ignition switch off and wait for at least 30 seconds.

  5. Turn the ignition switch to ON and turn the GTS on.

  6. Wait 5 seconds or more.

  7. Enter the following menus: Powertrain / Engine and ECT / Trouble Codes.

  8. Read the pending DTCs.

    Tip:
    • If a pending DTC is output, the system is malfunctioning.

    • If a pending DTC is not output, perform the following procedure.

  9. Enter the following menus: Powertrain / Engine and ECT / Utility / All Readiness.

  10. Input the DTC: P0102 or P0103.

  11. Check the DTC judgment result.

    GTS Display

    Description

    NORMAL

    • DTC judgment completed

    • System normal

    ABNORMAL

    • DTC judgment completed

    • System abnormal

    INCOMPLETE

    • DTC judgment not completed

    • Perform driving pattern after confirming DTC enabling conditions

    N/A

    • Unable to perform DTC judgment

    • Number of DTCs which do not fulfill DTC preconditions has reached ECU memory limit

    Tip:
    • If the judgment result shows NORMAL, the system is normal.

    • If the judgment result shows ABNORMAL, the system has a malfunction.

    • If the judgment result shows INCOMPLETE or N/A, perform the Confirmation Driving Pattern and check the DTC judgment result again.

WIRING DIAGRAM

A298875E08

CAUTION / NOTICE / HINT

Note:

Inspect the fuses for circuits related to this system before performing the following procedure.

Tip:

Read freeze frame data using the GTS. 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 DTC OUTPUT (DTC P0102 OR P0103)

    1. Connect the GTS to the DLC3.

    2. Turn the ignition switch to ON.

    3. Turn the GTS on.

    4. Enter the following menus: Powertrain / Engine and ECT / Trouble Codes.

      Powertrain > Engine and ECT > Trouble Codes

    5. Read DTCs.

      Result

      Result

      Proceed to

      DTC P0102 is output

      A

      DTC P0103 is output

      B

    B

    CHECK HARNESS AND CONNECTOR (SENSOR GROUND)Click here

    A
  2. CHECK TERMINAL VOLTAGE (POWER SOURCE OF MASS AIR FLOW METER SUB-ASSEMBLY)

    1. A127724C05

      *a

      Front view of wire harness connector

      (to Mass Air Flow Meter Sub-assembly)

      Disconnect the mass air flow meter sub-assembly connector.

    2. Turn the ignition switch to ON.

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

      Standard Voltage

      Tester Connection

      Condition

      Specified Condition

      B1-3 (+B) - Body ground

      Ignition switch ON

      11 to 14 V

    Result

    Proceed to

    OK

    NG

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR (MASS AIR FLOW METER SUB-ASSEMBLY - EFI-MAIN NO.1 RELAY)

    OK
  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

      Tester Connection

      Condition

      Specified Condition

      B1-5 (VG) - B93-137 (VG)

      Always

      Below 1 Ω

      B1-4 (E2G) - B93-104 (E2G)

      Always

      Below 1 Ω

      B1-5 (VG) or B93-137 (VG) - Body ground

      Always

      10 kΩ or higher

    Result

    Proceed to

    OK

    NG

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK
  4. INSPECT MASS AIR FLOW METER SUB-ASSEMBLY

    1. Inspect the mass air flow meter sub-assembly, referring to the On-vehicle Inspection for Mass Air Flow Meter (Click here).

    2. Inspect the mass air flow meter sub-assembly, referring to the Inspection for Mass Air Flow Meter (Click here).

    3. Inspect the function of the mass air flow meter sub-assembly.

      1. Connect the GTS to the DLC3.

      2. Turn the ignition switch to ON.

      3. Turn the GTS on.

      4. Enter the following menus: Powertrain / Engine and ECT / Data List / All Data / MAF.

        Powertrain > Engine and ECT > Data List

        Tester Display

        MAF

      5. Start the engine.

      6. Check that the MAF value changes when the engine is raced.

        OK

        The reading changes.

        Tip:

        Perform "Inspection After Repair" after replacing the mass air flow meter sub-assembly (Click hereClick here).

    Result

    Proceed to

    OK

    NG

    OK

    REPLACE ECM

    NG

    REPLACE MASS AIR FLOW METER SUB-ASSEMBLY

  5. CHECK HARNESS AND CONNECTOR (SENSOR GROUND)

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

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

      Standard Resistance

      Tester Connection

      Condition

      Specified Condition

      B1-4 (E2G) - Body ground

      Always

      Below 1 Ω

      Tip:

      Perform "Inspection After Repair" after replacing the mass air flow meter sub-assembly (Click hereClick here).

    Result

    Proceed to

    OK

    NG

    OK

    REPLACE MASS AIR FLOW METER SUB-ASSEMBLY

    NG
  6. 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

      Tester Connection

      Condition

      Specified Condition

      B1-4 (E2G) - B93-104 (E2G)

      Always

      Below 1 Ω

    Result

    Proceed to

    OK

    NG

    OK

    REPLACE ECM

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR