SFI SYSTEM(w/o EGR 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 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 duration and to provide an 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 specific 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 are 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.

A01H5YCE16
*1 Temperature Sensor (Thermistor)
*2 Power Transistor
*3 Platinum Hot Wire (Heater)
*4 Output Voltage
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 less than 0.2 V for 3 seconds.

(1 trip detection logic: Engine speed is less than 4000 rpm)

(2 trip detection logic: Engine speed is 4000 rpm or higher)


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

  • Mass air flow meter sub-assembly

  • EFI-MAIN relay

  • 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: Engine speed is less than 4000 rpm)

(2 trip detection logic: Engine speed is 4000 rpm or higher)


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

  • Mass air flow meter sub-assembly

  • EFI-MAIN relay

  • ECM

Comes on DTC stored

Tech Tips

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

271.0 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 less than 0.2 V, or higher than 4.9 V for 3 seconds, the ECM stores a DTC.

MONITOR STRATEGY

Frequency of Operation Continuous

CONFIRMATION DRIVING PATTERN


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

WIRING DIAGRAM

A01H7ADE05

CAUTION / NOTICE / HINT

Note

Inspect the fuses for circuits related to this system before performing the following 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 OUTPUT DTC (DTC P0102 OR P0103)


    1. Connect the GTS to the DLC3.

    2. Turn the power switch on (IG).

    3. Turn the GTS on.

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

    5. Read the DTCs.


      Powertrain > Engine and ECT > Trouble Codes
      Result
      Result Proceed to
      DTC P0102 is output A
      DTC P0103 is output B

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

    A01H5S7C24
    *a

    Front view of wire harness connector

    (to Mass Air Flow Meter Sub-assembly)


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

    2. Turn the power switch on (IG).

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

      Standard Voltage
      Tester Connection Condition Specified Condition
      C1-3 (+B) - Body ground Power switch on (IG) 11 to 14 V
      Result
      Proceed to
      OK
      NG

    NG
    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
      C1-5 (VG) - C48-91 (VG) Always Below 1 Ω
      C1-4 (E2G) - C48-92 (E2G) Always Below 1 Ω
      C1-5 (VG) or C48-91 (VG) - Body ground Always 10 kΩ or higher
      Result
      Proceed to
      OK
      NG

    NG
    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 power switch on (IG).

      3. Turn the GTS on.

      4. Put the engine in inspection mode (maintenance mode).

        Click here


        Powertrain > Hybrid Control > Utility
        Tester Display
        Inspection Mode
      5. Enter the following menus: Powertrain / Engine and ECT / Data List / Primary / MAF.


        Powertrain > Engine and ECT > Data List
        Tester Display
        MAF
      6. Start the engine.

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

        OK
        The reading changes.

        Tech Tips

        Perform "Inspection After Repair" after replacing the mass air flow meter sub-assembly.

        Click here

      Result
      Proceed to
      OK
      NG

    OK
    NG
  5. CHECK HARNESS AND CONNECTOR (MASS AIR FLOW METER SUB-ASSEMBLY - EFI-MAIN RELAY)


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

    2. Remove the EFI-MAIN relay from the No. 1 engine room relay block and junction block assembly.

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

      Standard Resistance
      Tester Connection Condition Specified Condition
      C1-3 (+B) - 3 (EFI-MAIN Relay) Always Below 1 Ω
      C1-3 (+B) or 3 (EFI-MAIN Relay) - Body ground Always 10 kΩ or higher
      Result
      Proceed to
      OK
      NG

    OK
    NG
  6. 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
      C1-4 (E2G) - Body ground Always Below 1 Ω

      Tech Tips

      Perform "Inspection After Repair" after replacing the mass air flow meter sub-assembly.

      Click here

      Result
      Proceed to
      OK
      NG

    OK
    NG
  7. 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
      C1-4 (E2G) - C48-92 (E2G) Always Below 1 Ω
      Result
      Proceed to
      OK
      NG

    OK
    NG