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 JUDGEMENT
Check Conditions
The actual volumetric efficiency is higher than the volumetric efficiency estimated by the throttle position sensor(main). Or, the actual volumetric efficiency is more than 60 %.
Engine speed is more than 750 r/min.
Judgement Criterion
The difference between the actual volumetric efficiency and the volumetric efficiency estimated by the throttle position sensor (main) is more than 35 %.
Check Conditions
The actual volumetric efficiency is higher than the volumetric efficiency estimated by the throttle position sensor(sub). Or, the actual volumetric efficiency is more than 60%.
Engine speed is more than 750 r/min.
Judgement Criterion
The 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 intake air system
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
Data list reference table (Refer to ).
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 ).