Code No. P0174: Left Bank Abnormal Fuel System (lean)






OPERATION



  • Refer to Code No. P0202: No. 2 Injector System .
  • Refer to Code No. P0204: No. 4 Injector System .
  • Refer to Code No. P0206: No. 6 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 Conditions
  • Engine coolant temperature is lower than 100°C when the engine is started.
  • Intake air temperature is lower than 60°C when the engine is started.
  • Under the closed loop air/fuel ratio control.
  • Engine coolant temperature is higher than 76°C.
  • Air flow sensor output is 12 g/sec or more.
Judgment Criterion
  • Long-term fuel trim has continued to be higher than +12.5 % for 5 seconds.


  • Short-term fuel trim has continued to be higher than +7.4 % for 5 seconds.
Check Conditions
  • Engine coolant temperature is lower than 100°C when the engine is started.
  • Intake air temperature is lower than 60°C when the engine is started.
  • Under the closed loop air/fuel ratio control.
  • Engine coolant temperature is higher than 76°C.
  • Air flow sensor output is 12 g/sec or less.
Judgment Criterion
  • Long-term fuel trim has continued to be higher than +12.5 % for 5 seconds.


  • Short-term fuel trim has continued to be higher than +12.5 % for 5 seconds.
Check Conditions
  • Engine coolant temperature is higher than 100°C when the engine is started.
  • Intake air temperature is higher than 60°C when the engine is started.
  • Under the closed loop air/fuel ratio control.
  • Engine coolant temperature is higher than 76°C.
  • Air flow sensor output is 12 g/sec or more.
Judgment Criterion
  • Long-term fuel trim has continued to be higher than +12.5 % for 5 seconds.


  • Short-term fuel trim has continued to be higher than 17.6 % for 5 seconds.
Check Conditions
  • Engine coolant temperature is higher than 100°C when the engine is started.
  • Intake air temperature is higher than 60°C when the engine is started.
  • Under the closed loop air/fuel ratio control.
  • Engine coolant temperature is higher than 76°C.
  • Air flow sensor output is 12 g/sec or less.
Judgment Criterion
  • Long-term fuel trim has continued to be higher than +12.5 % for 5 seconds.


  • Short-term fuel trim has continued to be higher than +22.3 % for 5 seconds.
Check Conditions
  • Engine coolant temperature is higher than 76°C.
  • Under the closed loop air/fuel ratio control.
Judgment Criterion
  • Long-term fuel trim has continued to be +12.5 % for 2 seconds.


  • Short-term fuel trim has continued to be +25.0 % for 2 seconds.

PROBABLE CAUSES



  • Failed intake air temperature sensor
  • Failed air flow sensor
  • Failed No. 2, No. 4 and No. 6 injector
  • Air drawn in from gaps in gasket, seals, etc.
  • Failed engine coolant temperature sensor
  • Failed manifold absolute pressure sensor
  • Failed barometric pressure sensor
  • Exhaust leak
  • Incorrect fuel pressure
  • Use of incorrect or contaminated fuel
  • Harness damage in injector circuit or loose connector contact
  • Failed engine-ECU

DIAGNOSIS PROCEDURE

STEP 1. Check for exhaust leaks

Q. Is the check result normal?
Go to Step 2 .
Repair.

STEP 2. Check for intake system vacuum leaks.

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

STEP 3. M.U.T.-III data list

  • Refer to Data List Reference Table .

  1. Item 05: Intake air temperature sensor
  2. Item 06: Engine coolant temperature sensor
  3. Item 08: Manifold absolute pressure sensor
  4. Item 10: Air flow sensor

Q. Are the check results normal?
Go to Step 4 .
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 4. M.U.T.-III data list

  • Refer to Data List Reference Table .

  1. Item BB: Barometric pressure sensor

Q. Is the check result normal?
Go to Step 5 .
Replace the engine-ECU.

STEP 5. Connector Check: Injector connector

  1. B-104 (No. 2 injector connector).
  2. B-106 (No. 4 injector connector).
  3. B-133 (No. 6 injector connector).

Q. Are the check results normal?
Go to Step 6 .
Repair or replace the connector.

STEP 6. Check No. 2, No. 4 and No. 6 injector itself.

  • Check No. 2, No. 4 and No. 6 injector itself (Refer to ).

Q. Are the check results normal?
Go to Step 7 .
Replace the injector.

STEP 7. Connector check: B-29 engine-ECU connector

Q. Is the check result normal?
Go to Step 8 .
Repair or replace the connector.

STEP 8. Check harness between injector connector and engine-ECU connector.

  1. Check harness between B-104 (terminal No. 2) No. 2 injector connector and B-29 (terminal No. 3) engine-ECU connector.
  2. Check harness between B-106 (terminal No. 2) No. 4 injector connector and B-29 (terminal No. 19) engine-ECU connector.
  3. Check harness between B-133 (terminal No. 2) No. 6 injector connector and B-29 (terminal No. 51) engine-ECU connector.

  • Check output line for damage.

Q. Are the check results normal?
Go to Step 9 .
Repair the damaged harness wire.

STEP 9. Fuel pressure measurement.

  • Fuel pressure measurement (Refer to Fuel Pressure Test ).

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

STEP 10. Check for entry of foreign matter (water, kerosene, etc.) into fuel.

Q. Is the check result normal?
Go to Step 11 .
Replace the fuel.

STEP 11. Replace No. 2, No. 4 and No. 6 injectors.

  • After replacing the injectors, re-check the trouble symptoms.

Q. Are the check results normal?
Check end.
Replace the engine-ECU.