Code No. P1235: 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 Conditions
  • Engine is running.
  • Throttle position sensor (main and sub) is normal.
Judgement Criteria
  • The difference between volumetric efficiency (actual measurement) by the air flow sensor and volumetric efficiency estimated from the throttle position sensor (main) exceeds the specified value.
  • The difference between volumetric efficiency (actual measurement) by the air flow sensor and volumetric efficiency estimated from the throttle position sensor (sub) exceeds the specified value.
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
  • Failed intake air system
  • There is some trash around air flow sensor
  • Failed supercharging pressure control system
  • Failed engine-ECU

DIAGNOSIS PROCEDURE

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

Q. Is any other diagnosis code than P1235 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?
Go to Step 3.
Check air flow sensor system (Refer to Code No. P0102: Air Flow Sensor Circuit Low Input , P0103: Air Flow Sensor Circuit High Input ).

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 trash around air flow sensor.

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

STEP 5. Check supercharging pressure.

  • Check supercharging pressure (Refer to GROUP 15 - On-vehicle Service - Supercharging Pressure Check ).

Q. Is the check result normal?
Go to Step 6.
Repair.

STEP 6. Check supercharging pressure control system.

  • Check supercharging pressure control system (Refer to GROUP 15 - On-vehicle Service - Supercharging Pressure Control System Check ).

Q. Is the check result normal?
Go to Step 7.
Repair.

STEP 7. 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 ).