Code No. P0171: Abnormal Fuel System (lean)






OPERATION



  • Refer to Code No. P0201: No. 1 Injector System .
  • Refer to Code No. P0202: No. 2 Injector System .
  • Refer to Code No. P0203: No. 3 Injector System .
  • Refer to Code No. P0204: No. 4 Injector System .

FUNCTION



  • If the fuel system goes out of order, the fuel correction value will become larger.
  • The engine-ECU checks whether the fuel trim value is within a specified range.

TROUBLE JUDGMENT


Check Condition
  • Engine: In learning the air-fuel ratio.
Judgement Criterion
  • The correction value of fuel injection amount is too high for 5 seconds or more.
FAIL-SAFE AND BACKUP FUNCTION
  • None.

PROBABLE CAUSES



  • Failed fuel system
  • Failed No. 1 intake air temperature sensor
  • Failed No. 2 intake air temperature sensor
  • Failed engine coolant temperature sensor
  • Failed air flow sensor
  • Failed manifold absolute pressure sensor
  • Failed barometric pressure sensor
  • Failed intake air system
  • Exhaust leak
  • Failed purge control solenoid valve
  • Incorrect fuel pressure
  • Failed engine-ECU
  • Failed injector
  • Harness damage in injector circuit or loose connector contact

DIAGNOSIS PROCEDURE

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

Q. Is diagnosis code set except P0171?
Inspection chart for diagnosis code (Refer to ).
Go to Step 2.

STEP 2. Check for exhaust leaks

Q. Is the check result normal?
Go to Step 3.
Repair.

STEP 3. Check air intake from inlet hose and inlet manifold.

Q. Is the check result normal?
Go to Step 4.
Repair.

STEP 4. M.U.T.-III data list

  • Refer to Data List Reference Table .

  1. Item 5: No. 1 intake air temperature sensor
  2. Item 6: Engine coolant temperature sensor
  3. Item 8: Manifold absolute pressure sensor
  4. Item 10: Air flow sensor
  5. Item BB: Barometric pressure sensor

Q. Are the check results normal?
Go to Step 5.
Perform the diagnosis code classified check procedure for the sensor that has shown an abnormal data value (Refer to Inspection Chart for Diagnosis Code ).

STEP 5. Check No. 2 intake air temperature sensor itself.

  • Check No. 2 intake air temperature sensor itself (Refer to ).

Q. Is the check result normal?
Go to Step 6.
Replace the No. 2 intake air temperature sensor.

STEP 6. Check purge control solenoid valve itself.

  • Check purge control solenoid valve itself (Refer to GROUP 17 - Emission Control <MPI> - Evaporative Emission Control System - Purge Control Solenoid Valve Check ).

Q. Is the check result normal?
Go to Step 7.
Replace the purge control solenoid valve.

STEP 7. Connector Check: Injector connectors

  1. B-101 (No. 1 injector connector).
  2. B-102 (No. 2 injector connector).
  3. B-103 (No. 3 injector connector).
  4. B-104 (No. 4 injector connector).

Q. Are the check results normal?
Go to Step 8.
Repair or replace the connector.

STEP 8. Check injector itself.

  • Check injector itself (Refer to ).

Q. Is the check result normal?
Go to Step 9.
Replace the injector.

STEP 9. Connector check: B-08 engine-ECU connector

Q. Is the check result normal?
Go to Step 10.
Repair or replace the connector.

STEP 10. Check harness between injector connector and engine-ECU connector.

  1. Check and repair harness between B-101 (terminal No. 2) No. 1 injector connector and B-08 (terminal No. 2) engine-ECU connector.
  2. Check and repair harness between B-102 (terminal No. 2) No. 2 injector connector and B-08 (terminal No. 3) engine-ECU connector.
  3. Check and repair harness between B-103 (terminal No. 2) No. 3 injector connector and B-08 (terminal No. 18) engine-ECU connector.
  4. Check and repair harness between B-104 (terminal No. 2) No. 4 injector connector and B-08 (terminal No. 19) engine-ECU connector.

  • Check output line for damage.

Q. Are the check results normal?
Go to Step 11.
Repair the damaged harness wire.

STEP 11. Fuel pressure measurement.

  • Fuel pressure measurement (Refer to ).

Q. Is the check result normal?
Go to Step 12.
Repair.

STEP 12. Check fuel.

  • Check for entry of foreign matter (water, diesel fuel, etc) into fuel.

Q. Is the check result normal?
Go to Step 13.
Replace the fuel.

STEP 13. Replace the injector.

  • After replacing the injector, reconfirm whether the diagnosis code is set.

Q. Is the diagnosis code set?
Replace the engine-ECU.
Check end.