Code No. P0101: Air Flow Sensor Range/Performance Problem <Euro4>

OPERATION

Power is supplied by the engine control relay terminal to the air flow sensor terminal, and the air flow sensor terminal is earthed through the engine-ECU AFSE.
The air flow sensor terminal outputs a sensor signal, which is input into the engine-ECU AFS.

FUNCTION

The air flow sensor outputs pulse signal that varies in accordance with the intake air volume.
In response to the signal, the engine-ECU controls EGR control, etc.

TROUBLE JUDGEMENT

Check Conditions

Battery positive voltage is 8 - 16 V
1 second before the throttle valve fully opened-position value after the ignition switch has been in "LOCK" (OFF) position.

Judgement Criterion

The air flow sensor output voltage is threshold value or less.

or

The air flow sensor output voltage is threshold value or more.

FAIL-SAFE AND BACKUP FUNCTION

The control is performed using the previous value.
The throttle valve is opened (Electrical discontinuity).
The EGR control is stopped (fully closed).

PROBABLE CAUSES

Failed air flow sensor
Harness damage in air flow sensor circuit or loose connector contact
Failed engine-ECU

DIAGNOSIS PROCEDURE

STEP 1. 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 2.

	Repair the damaged harness wire.

STEP 2. Check harness between air flow sensor connector terminal and engine-ECU connector terminal AFS.

Check output line for damage.

Q. Is the check result normal?

	Go to Step 3.

	Repair the damaged harness wire.

STEP 3. Check harness between air flow sensor connector terminal and engine-ECU connector terminal AFSE.

Check earthing line for damage.

Q. Is the check result normal?

	Go to Step 4.

	Repair the damaged harness wire.

STEP 4. M.U.T.-III data list

Refer to Data List Reference Table .

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 5.

STEP 5. Replace the air flow sensor.

After replacing the air flow sensor, re-check the trouble symptoms.

Q. Is the check result normal?

	Check end.

	Replace the engine-ECU.