Code No. P0102: Air Flow Sensor Circuit Low Input




OPERATION




FUNCTION




TROUBLE JUDGMENT


Check Condition
Judgement Criterion

FAIL-SAFE AND BACKUP FUNCTION




PROBABLE CAUSES




DIAGNOSIS PROCEDURE


STEP 1. M.U.T.-III data list



  • Data list reference table (Refer to ).

  1. Item 10: Air flow sensor

Q. Is the check result normal?

Intermittent malfunction (Refer to GROUP 00 - How to Use Troubleshooting/Inspection Service Points - How to Cope with Intermittent Malfunctions ).
Go to Step 2.

STEP 2. Perform voltage measurement at air flow sensor connector.



  • Disconnect connector, and measure at harness side.
  • Ignition switch: "ON"
  • Voltage between terminal power supply line and body earth.
OK: System voltage

Q. Is the check result normal?

Go to Step 3.

    Repair or replace the connector, or check and repair harness between engine control relay connector terminal and air flow sensor connector terminal.

    • Check power supply line for open/short circuit.

STEP 3. Perform voltage measurement at air flow sensor connector.



  • Use special tool test harness (MB991709) to connect connector, and measure at pick-up harness.
  • Ignition switch: "ON"
  • Voltage between terminal engine-ECU AFS5 line and body earth.
OK: 4.9 - 5.1 V

Q. Is the check result normal?

Go to Step 5.
Go to Step 4.

STEP 4. Perform voltage measurement at engine-ECU connector.



  • Measure engine-ECU connector terminal voltage.
  • Ignition switch: "ON"
  • Voltage between terminal AFS5 and body earth.
OK: 4.9 - 5.1 V

Q. Is the check result normal?

Go to Step 5.

    Repair or replace the connector, or check and repair harness between engine-ECU connector terminal AFS5 and air flow sensor connector terminal.

    • Check power supply line for open/short circuit.

STEP 5. Check harness between air flow sensor connector terminal and engine-ECU connector terminal AFS.



  • Check output line for open/short circuit and damage.

Q. Is the check result normal?

Go to Step 6.
Repair or replace the connector, or repair the damaged harness wire.

STEP 6. Check harness between engine control relay connector terminal and air flow sensor connector terminal.



  • Check power supply line for damage.

Q. Is the check result normal?

Go to Step 7.
Repair or replace the connector, or repair the damaged harness wire.

STEP 7. M.U.T.-III data list



  • Data list reference table (Refer to ).

  1. Item 10: Air flow sensor

Q. Is the check result normal?

Intermittent malfunction (Refer to GROUP 00 - How to Use Troubleshooting/Inspection Service Points - How to Cope with Intermittent Malfunctions ).
Go to Step 8.

STEP 8. Replace the air flow sensor



  • After replacing the air flow sensor, reconfirm whether the diagnosis code is set.

Q. Is the diagnosis code set?

Replace the engine-ECU.
Check end.