Code No. P0100: Air Flow Sensor System

OPERATION

Power is supplied by the engine control relay (terminal No. 1) to the air flow sensor (terminal No. 2), and the air flow sensor (terminal No. 4) is earthed through the engine-A/T-ECU (terminal No. 96).
The air flow sensor (terminal No. 3) outputs a sensor signal, which is input into the engine-A/T-ECU (terminal No. 63).

FUNCTION

The air flow sensor outputs amperage that varies in accordance with the intake air volume.
The engine-A/T-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 Conditions

After 3 seconds have passed since the ignition switch was turned to ON position.

Judgment Criteria

Air flow sensor output voltage has continued to be 0.2 V or less for 2 seconds.

Air flow sensor output voltage has continued to be 4.9 V or more for 2 seconds.

PROBABLE CAUSE

Failed air flow sensor
Open/short circuit in air flow sensor circuit or loose connector contact
Failed engine-A/T-ECU

DIAGNOSIS PROCEDURE

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

Refer to Data List Reference Table .

Item 12: Air flow sensor

Q. Is the check result normal?

	Intermittent malfunction (Refer to GROUP 00 - How to Use Troubleshooting/Inspection Service Points ).

	Go to Step 2 .

STEP 2. Connector check: B-106 air flow sensor connector

Q. Is the check result normal?

Go to Step 3 .

Repair or replace.

STEP 3. Perform voltage measurement at B-106 air flow sensor connector.

Disconnect connector, and measure at harness side.
Ignition switch: ON
Voltage between terminal No. 2 and earth.

OK: System voltage

Q. Is the check result normal?

Go to Step 5 .

Go to Step 4 .

STEP 4. Connector check: B-15X engine control relay connector

Q. Is the check result normal?

Check power supply line for open/short circuit.

Repair or replace.

STEP 5. Check resistance measurement at B-106 air flow sensor connector.

Disconnect and measure at harness side.
Resistance between terminal No. 4 and earth.

OK: 2 Ω or less

Q. Is the check result normal?

Go to Step 9 .

Go to Step 6 .

STEP 6. Connector check: C-113 engine-A/T-ECU connector

Q. Is the check result normal?

Go to Step 7 .

Repair or replace.

STEP 7. Check harness between B-106 (terminal No. 4) air flow sensor connector and C-113 (terminal No. 96) engine-A/T-ECU connector.

note

Before checking harness, check intermediate connector C-116, and repair if necessary.

Check earthing line for open circuit and damage.

Q. Is the check result normal?

Go to Step 8 .

Repair.

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

Refer to Data List Reference Table .

Item 12: Air flow sensor

Q. Is the check result normal?

	Intermittent malfunction (Refer to GROUP 00 - How to Use Troubleshooting/Inspection Service Points ).

	Replace engine-A/T-ECU.

STEP 9. Connector check: C-112 engine-A/T-ECU connector.

Q. Is the check result normal?

Go to Step 10 .

Repair or replace.

STEP 10. Check harness between B-106 (terminal No. 3) air flow sensor connector and C-112 (terminal No. 63) engine-A/T-ECU connector.

Check output line for open/short circuit and damage.

Q. Is the check result normal?

Go to Step 11 .

Repair.

STEP 11. Connector check: B-15X engine control relay connector

Q. Is the check result normal?

Go to Step 12 .

Repair or replace.

STEP 12. Check harness between B-106 (terminal No. 2) air flow sensor connector and B-15X (terminal No. 1) engine control relay connector.

note

Before checking harness, check intermediate connector C-116, and repair if necessary.

Check power supply line for damage.

Q. Is the check result normal?

Go to Step 13 .

Repair.

STEP 13. M.U.T.-III data list

Refer to Data List Reference Table .

Item 12: Air flow sensor

Q. Is the check result normal?

	Intermittent malfunction (Refer to GROUP 00 - How to Use Troubleshooting/Inspection Service Points ).

	Replace air flow sensor. Then go to Step 14 .

STEP 14. M.U.T.-III diagnosis code

Reconfirmation of diagnosis code.

Q. Is the diagnosis code set?

	Replace the engine-A/T-ECU.

	Check end.