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 ).