SFI SYSTEM, Diagnostic DTC:P0102, P0103

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

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 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 these components in the mass air flow 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 speed and throttle valve position. Fail safe mode continues until a pass condition is detected.

A015ZQ0E01
DTC No. DTC Detection Condition Trouble Area
P0102 Mass air flow meter voltage is less than 0.2 V for 3 seconds

  • Open or short in mass air flow meter circuit

  • Short in ground circuit

  • Mass air flow meter

  • ECM
P0103 Mass air flow meter voltage is more than 4.9 V for 3 seconds

  • Open or short in mass air flow meter circuit

  • Mass air flow meter

  • ECM

Tech Tips

When any of these DTCs are set, check the air-flow rate by entering the following menus: Powertrain / Engine / Data List / MAF.

Mass Air Flow Rate (g/sec.) Malfunction
Approximately 0.0

  • Open in mass air flow meter power source circuit

  • Open or short in VG circuit
271.0 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 and sets a DTC.

Example:

When the sensor output voltage remains less than 0.2 V, or more than 4.9 V, for 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

A0161ZKE05

INSPECTION PROCEDURE

Note

Inspect the fuses for circuits related to this system before performing the following 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 DTC OUTPUT


    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 / DTC.

    5. Read the DTCs.

      Result
      Result Proceed to
      DTC P0102 is output A
      DTC P0103 is output B

    B

    INSPECT MASS AIR FLOW METER (SENSOR GROUND) Click here

    A

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


    1. A0161I3E14

      Disconnect the mass air flow meter connector.

    2. Turn the engine switch on (IG).

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

      Standard Voltage
      Tester Connection Switch Condition Specified Condition
      E29-3 (+B) - Body ground Engine switch on (IG) 11 to 14 V

    4. Reconnect the mass air flow meter connector.


    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR (MASS AIR FLOW METER - EFI MAIN RELAY)

    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
      E29-5 (VG) - E3-25 (VG) Always Below 1 Ω
      E29-4 (E2G) - E3-24 (E2G) Always Below 1 Ω
      Standard Resistance (Check for Short)
      Tester Connection Condition Specified Condition
      E29-5 (VG) or E3-25 (VG) - Body ground Always 10 kΩ or higher

    4. Reconnect the mass air flow meter connector.

    5. Reconnect the ECM connector.


    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

  4. INSPECT MASS AIR FLOW METER


    1. Perform On-vehicle Inspection Click here.

    2. Perform Inspection Click here.

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


      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 / Data List / MAF.

      5. Start the engine.

      6. Check that the reading of the MAF changes when the engine is raced.

        OK
        The reading changes.

    NG

    REPLACE MASS AIR FLOW METER Click here

    OK

    REPLACE ECM Click here

  5. INSPECT MASS AIR FLOW METER (SENSOR GROUND)


    1. A0161I3E16

      Disconnect the mass air flow meter connector.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      E29-4 (E2G) - Body ground Always Below 1 Ω

    3. Reconnect the mass air flow meter connector.


    NG

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

    OK

    REPLACE MASS AIR FLOW METER Click here

  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
      E29-4 (E2G) - E3-24 (E2G) Always Below 1 Ω

    4. Reconnect the mass air flow meter connector.

    5. Reconnect the ECM connector.


    NG

    REPAIR OR REPLACE HARNESS OR CONNECTOR

    OK

    REPLACE ECM Click here