SFI SYSTEM, Diagnostic DTC:P0102, P0103

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

DESCRIPTION

The mass air flow 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 the appropriate air fuel ratio.

Inside the mass air flow 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 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.

Tech Tips

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.

A004HEFE37
*1 Temperature Sensor (Thermistor)
*2 Power Transistor
*3 Platinum Hot Wire (Heater)
*4 Output Voltage
DTC No. DTC Detection Condition Trouble Area
P0102

Mass air flow meter voltage is 0.127 V or less for 0.5 seconds or more.

(1 trip detection logic)

  • Open or short in mass air flow meter circuit

  • Mass air flow meter

  • ECM
P0103

Mass air flow meter voltage is 4.723 V or more for 0.5 seconds or more.

(1 trip detection logic)

Tech Tips

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

Mass Air Flow Rate (gm/sec) Malfunction
Approximately 0.0

  • Open in mass air flow meter power source circuit

  • Open or short in VG circuit
160.0 or more

  • Open in E2G circuit

MONITOR DESCRIPTION

If there is a defect in the mass air flow 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 mass air flow meter circuit and stores a DTC.

CONFIRMATION DRIVING PATTERN


  1. A004ISCE17

  2. Connect the GTS to the DLC3.

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

  4. Clear DTCs (even if no DTCs are stored, perform the clear DTC operation) Click here.

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

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

  7. Start the engine and warm it up until the engine coolant temperature reaches 75°C (167°F) or higher.

  8. With the vehicle stationary, depress the accelerator pedal and maintain an engine speed of between 2500 and 3000 rpm for 40 seconds or more [A].

  9. Drive the vehicle at 10 km/h (6.25 mph) or more for 1 minute or more [B].

    CAUTION:

    When performing the confirmation driving pattern, obey all speed limits and traffic laws.

  10. Enter the following menus: Powertrain / Engine / Trouble Codes.

  11. Read pending DTCs.

    Tech Tips


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

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

  12. Enter the following menus: Powertrain / Engine / Utility / All Readiness.

  13. Input the DTC: P0102 or P0103.

  14. 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

    Tech Tips


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

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

  15. If the test result is INCOMPLETE or N/A and no DTC is output, perform a universal trip and check for permanent DTCs Click here.

    Tech Tips


    • If a permanent DTC is output, the system is malfunctioning.

    • If no permanent DTC is output, the system is normal.

WIRING DIAGRAM

A004JXNE03

CAUTION / NOTICE / HINT

Note

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

Tech Tips

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


    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 / 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)

    A004HTZE03
    Text in Illustration
    *a

    Front view of wire harness connector

    (to Mass Air Flow Meter)

    1. Disconnect the mass air flow meter 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 Switch Condition Specified Condition
      C16-3 (+B) - Body ground Ignition switch ON 11 to 14 V

    NG

    CHECK RELAY (EFI MAIN1) Click here

    OK

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


    1. Disconnect the mass air flow meter 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
      C33-22 (VG) - C16-5 (VG) Always Below 1 Ω
      C33-29 (E2G) - C16-4 (E2G) Always Below 1 Ω
      Standard Resistance (Check for short)
      Tester Connection Condition Specified Condition
      C33-22 (VG) or C16-5 (VG) - Body ground Always 10 kΩ or higher
      C33-29 (E2G) or C16-4 (E2G) - Body ground Always 10 kΩ or higher

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

  4. INSPECT MASS AIR FLOW METER


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

    2. Inspect the mass air flow meter, referring to the Inspection for Mass Air Flow Meter Click here.

    3. Inspect the function of the mass air flow meter.


      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 / Data List / MAF.

      5. Start the engine.

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

        OK
        The reading changes.

    OK

    REPLACE ECM Click here

    NG

    REPLACE MASS AIR FLOW METER Click here

  5. CHECK HARNESS AND CONNECTOR (SENSOR GROUND)


    1. Disconnect the mass air flow meter connector.

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

      Standard Resistance (Check for open)
      Tester Connection Condition Specified Condition
      C16-4 (E2G)- Body ground Always Below 1 Ω

    OK

    REPLACE MASS AIR FLOW METER Click here

    NG

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


    1. Disconnect the mass air flow meter 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
      A33-29 (E2G) - C16-4 (E2G) Always Below 1 Ω
      Standard Resistance (Check for short)
      Tester Connection Condition Specified Condition
      A33-29 (E2G) or C16-4 (E2G) - Body-ground Always 10 kΩ or higher

    OK

    REPLACE ECM Click here

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

  7. CHECK RELAY (EFI MAIN1)


    1. Inspect the EFI MAIN1 relay Click here.


    NG

    REPLACE RELAY (EFI MAIN1)

    OK

  8. CHECK HARNESS AND CONNECTOR (MASS AIR FLOW METER - EFI MAIN1 RELAY)


    1. Disconnect the mass air flow meter connector.

    2. Remove the EFI MAIN1 relay from the engine room relay block assembly.

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

      Standard Resistance (Check for open)
      Tester Connection Condition Specified Condition
      EFI MAIN1 relay terminal 3 - C16-3 (+B) Always Below 1 Ω
      Standard Resistance (Check for short)
      Tester Connection Condition Specified Condition
      EFI MAIN1 relay terminal 3 or C16-3 (+B) - Body ground Always 10 kΩ or higher

    OK

    CHECK ECM POWER SOURCE CIRCUIT Click here

    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR