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 or sub) signal.

TROUBLE JUDGMENT


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

PROBABLE CAUSES



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

DIAGNOSIS PROCEDURE

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

Q. Is any other diagnosis code than P1238 output?
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 (Refer to Code No. P0102 and Code No. P0103 ).