Code No. P0103: Air Flow Sensor Circuit High Input


OPERATION



  • Power is supplied by the engine control relay (terminal No. 2) to the air flow sensor (terminal No. 2), and the air flow sensor (terminal No. 4) is earthed through the engine-ECU (terminal No. 88).
  • The air flow sensor (terminal No. 3) outputs a sensor signal, which is input into the engine-ECU (terminal No. 87).

FUNCTION



  • The air flow sensor outputs current that varies in accordance with the intake air volume.
  • The engine-ECU uses the amperage output by the air flow sensor and the engine speed signal in order to determine the basic injection duration of the injector.

TROUBLE JUDGMENT


Check Condition
  • More than 3 seconds have passed since the ignition switch was turned to "ON" position.
Judgement Criterion
  • Air flow sensor output voltage is more than 4.9 V (corresponding to an air flow rate of 340 g/sec or more) for 2 seconds.

FAIL-SAFE AND BACKUP FUNCTION



  • Fuel control is carried out using throttle opening degree and engine speed in accordance with preset map.

PROBABLE CAUSES



  • Failed air flow sensor
  • Open circuit or harness damage in air flow sensor circuit or loose connector contact
  • Failed engine-ECU

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. Connector check: A-07 air flow sensor connector

Q. Is the check result normal?
Go to Step 3 .
Repair or replace the connector.

STEP 3. Perform resistance measurement at A-07 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 7 .
Go to Step 4 .

STEP 4. Connector check: B-27 engine-ECU connector

Q. Is the check result normal?
Go to Step 5 .
Repair or replace the connector.

STEP 5. Check harness between A-07 (terminal No. 4) air flow sensor connector and B-27 (terminal No. 88) engine-ECU connector.

  • Check earthing line for open circuit and damage.

Q. Is the check result normal?
Go to Step 6 .
Repair the damaged harness wire.

STEP 6. 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 ).
Replace the engine-ECU.

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.