Code No. P0102: Air flow Sensor Circuit Low Input




OPERATION



FUNCTION



TROUBLE JUDGMENT


Check Conditions
Judgment Criterion

PROBABLE CAUSES



DIAGNOSIS PROCEDURE

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



  • Refer to Data List Reference Table .

    1. Item 114: 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. Connector check: A-135 air flow sensor connector

Q. Is the check result normal?

Go to Step 3 .

Repair or replace the connector.

STEP 3. Perform voltage measurement at A-135 air flow sensor connector.


  • Disconnect connector, and measure at harness side.
  • Ignition switch: ON
  • Voltage between terminal No. 5 and earth.
OK: System voltage

Q. Is the check result normal?

Go to Step 5 .

Go to Step 4 .

STEP 4. Connector check: A-20X engine control relay connector


Q. Is the check result normal?


    Check and repair harness between A-20X (terminal No. 3) engine control relay connector and A-135 (terminal No. 5) air flow sensor connector.

    • Check power supply for open/short circuit.

Repair or replace the connector.

STEP 5. Perform resistance measurement at A-135 air flow sensor connector.


  • Disconnect connector, and measure at harness side.
  • Resistance between terminal No. 4 and earth.
OK: Continuity (2 Ω or less)

Q. Is the check result normal?

Go to Step 9 .

Go to Step 6 .

STEP 6. Connector check: C-103 engine-ECU connector

Q. Is the check result normal?

Go to Step 7 .

Repair or replace the connector.

STEP 7. Check harness between A-135 (terminal No. 4) air flow sensor connector and C-103 (terminal No. 155) engine-ECU connector.



  • Check earthing line for damage.

Q. Is the check result normal?

Go to Step 8 .

Repair the damaged harness wire.

STEP 8. M.U.T.-III data list



  • Refer to Data List Reference Table .

    1. Item 114: 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 ).

Replace the engine-ECU. After replacing the engine-ECU, register the injector identification code and learn fuel injection (Refer to GROUP 00 - Precautions Before Service - What The Common Rail Engine Learns ).

STEP 9. Perform voltage measurement at A-135 air flow sensor connector.


  • Disconnect connector, and measure at harness side.
  • Voltage between terminal No. 3 and earth.
OK: 4.9 - 5.1 V

Q. Is the check result normal?

Go to Step 12 .

Go to Step 10 .

STEP 10. Connector check: C-103 engine-ECU connector

Q. Is the check result normal?


    Go to Step 11 .

Repair or replace the connector.

STEP 11. Check harness between A-135 (terminal No. 3) air flow sensor connector and C-103 (terminal No. 140) engine-ECU connector.



  • Check output line for short circuit.

Q. Is the check result normal?

Replace the air flow sensor.

Repair the damaged harness wire.

STEP 12. Perform voltage measurement at C-103 engine-ECU connector.



  • Measure engine-ECU terminal voltage.
  • Disconnect A-135 air flow sensor connector.
  • Ignition switch: ON
  • Voltage between terminal No. 140 and earth.
OK: 4.9 - 5.1 V

Q. Is the check result normal?

Go to Step 14 .

Go to Step 13 .

STEP 13. Connector check: C-103 engine-ECU connector


Q. Is the check result normal?


    Check and repair harness between A-135 (terminal No. 3) air-flow sensor connector and C-103 (terminal No. 140) engine-ECU connector.

    • Check output line for open circuit.

Repair or replace the connector.

STEP 14. Connector check: C-103 engine-ECU connector

Q. Is the check result normal?

Go to Step 8 .

Repair or replace the connector.