Code No. P1238: Air Flow Sensor Trustful For Torque Monitoring




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 Conditions
  • Difference between the actual volumetric efficiency and the volumetric efficiency estimated by the throttle position sensor (main) is more than 0 %. Or, the volumetric efficiency is less than 60 %.
  • Engine speed is more than 750 r/min.
Judgement Criterion
  • Difference between the actual volumetric efficiency and the volumetric efficiency estimated by the throttle position sensor (main) is more than 35 %.
Check Conditions
  • Difference between the actual volumetric efficiency and the volumetric efficiency estimated by the throttle position sensor (sub) is more than 0 %. Or, the volumetric efficiency is less than 60 %.
  • Engine speed is more than 750 r/min.
Judgement Criterion
  • Difference between the actual volumetric efficiency and the volumetric efficiency estimated by the throttle position sensor (sub) is more than 35 %.

FAIL-SAFE AND BACKUP FUNCTION



  • Throttle opening degree position is in default position.

PROBABLE CAUSES



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

DIAGNOSIS PROCEDURE


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


Q. Is any other diagnosis code than P1238 set?

Inspection chart for diagnosis code (Refer to ).
Go to Step 2.

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



  • Refer to Data List Reference Table .

  1. Item 10: Air flow sensor

Q. Is the check result normal?

Replace the engine-ECU.
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 ).