Code No. P0172: Abnormal Fuel System (Rich)






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 Conditions
  • 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.
Judgement Criterion
  • Long-term fuel trim has continued to be lower than -12.5 % for 5 seconds.


  • Short-term fuel trim has continued to be lower than -7.4 % for 5 seconds.
Check Conditions
  • 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.
Judgement Criterion
  • Long-term fuel trim has continued to be lower than -12.5 % for 5 seconds.


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


  • Short-term fuel trim has continued to be -50.0 % for 2 seconds.

PROBABLE CAUSES



  • Failed intake air temperature sensor
  • Failed air flow sensor
  • Failed injector
  • Air drawn in from gaps in gasket, seals, etc.
  • Failed engine coolant temperature sensor
  • Failed barometric pressure sensor
  • Failed manifold absolute pressure sensor
  • Exhaust leak
  • Incorrect fuel pressure
  • Harness damage in injector circuit or loose connector contact
  • Failed engine-ECU

DIAGNOSIS PROCEDURE

STEP 1. M.U.T.-III data list

  • Refer to Data List Reference Table .

  1. Item 5: Intake air temperature sensor
  2. Item 6: Engine coolant temperature sensor
  3. Item 8: Manifold absolute pressure sensor
  4. Item 10: Air flow sensor

Q. Are the check results normal?
Go to Step 2 .
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 2. 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 3 .
Replace the engine-ECU.

STEP 3. Connector check: A-13 intermediate connector.

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

STEP 4. Check harness between A-13 intermediate connector and injector connector.

  1. Check and repair harness between A-13 (terminal No. 7) intermediate connector and B-102 (terminal No. 1) No. 1 injector connector.
  2. Check and repair harness between A-13 (terminal No. 7) intermediate connector and B-104 (terminal No. 1) No. 2 injector connector.
  3. Check and repair harness between A-13 (terminal No. 7) intermediate connector and B-105 (terminal No. 1) No. 3 injector connector.
  4. Check and repair harness between A-13 (terminal No. 7) intermediate connector and B-106 (terminal No. 1) No. 4 injector connector.

  • Check power supply line for damage.

Q. Are the check results normal?
Go to Step 5 .
Repair the damaged harness wire.

STEP 5. Check injector itself.

  • Check Injector itself (Refer to Injector Check ).

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

STEP 6. Fuel pressure measurement.

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

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

STEP 7. Replace the injector.

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

Q. Is the check result normal?
Check end.
Replace the engine-ECU.