Code No. P0068: Trustful Check Air Flow Sensor


FUNCTION



  • Compare the actual measurement of volumetric efficiency by an air flow sensor signal with volumetric efficiency estimated from a throttle position sensor (main and sub) signal.

TROUBLE JUDGMENT


Check Condition
  • Plausibility error of the throttle position sensor (main) is detected.
  • Plausibility error of the throttle position sensor (sub) is detected.
Judgement Criterion
  • Difference between the volumetric efficiency estimated by the throttle position sensor (main) and the volumetric efficiency estimated by the throttle position sensor (sub) is less than 8.8 %.

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
  • Harness damage in air flow sensor circuit or loose connector contact
  • There is some foreign matter around air flow sensor
  • Failed engine-ECU

DIAGNOSIS PROCEDURE

STEP 1. M.U.T.-III diagnosis code

Q. Is any other diagnosis code than P0068 set?
Inspection chart for diagnosis code (Refer to ).
Go to Step 2 .

STEP 2. M.U.T.-III data list

  • Data list reference table (Refer to ).

  1. Item 10: Air flow sensor

Q. Is the check result normal?
Go to Step 3 .
Check air flow sensor system. Check code No. P0102: air flow sensor circuit low input (Refer to ). Check code No. P0103: air flow sensor circuit high input (Refer to ).

STEP 3. Check air intake from inlet hose and inlet manifold.

Q. Is the check result normal?
Go to Step 4 .
Repair.

STEP 4. Check air flow sensor.

  • Check that there is not foreign matter around air flow sensor.

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

STEP 5. M.U.T.-III diagnosis code

  • Reconfirmation of diagnosis code.

Q. Is diagnosis code set?
Replace the engine-ECU.
Intermittent malfunction (Refer to GROUP 00 - How to Use Troubleshooting/Inspection Service Points - How to Cope with Intermittent Malfunctions ).