Code No. P0172: Abnormal Fuel System (rich) <Except Euro2>

OPERATION

Check code No. P0261: No. 1 injector circuit low input (Refer to ).
Check code No. P0262: No. 1 injector circuit high input (Refer to ).
Check code No. P0264: No. 2 injector circuit low input (Refer to ).
Check code No. P0265: No. 2 injector circuit high input (Refer to ).
Check code No. P0267: No. 3 injector circuit low input (Refer to ).
Check code No. P0268: No. 3 injector circuit high input (Refer to ).
Check code No. P0270: No. 4 injector circuit low input (Refer to ).
Check code No. P0271: No. 4 injector circuit high input (Refer to ).

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 JUDGEMENT

Check Conditions

Under the closed loop air/fuel ratio control.
Engine coolant temperature is more than 76°C.
Air flow sensor output is more than 6.4 g/sec.

Judgement Criterion

Long-term fuel trim is less than -12.5 % for 5 seconds.

or

Short-term fuel trim is less than -10.2 % for 5 seconds.

Check Conditions

Engine coolant temperature is more than 76°C.
Under the closed loop air/fuel ratio control.

Judgement Criterion

Long-term fuel trim is -12.5 % for 2 seconds.

or

Short-term fuel trim is -25.0 % for 2 seconds.

FAIL-SAFE AND BACKUP FUNCTION

None

PROBABLE CAUSES

Failed intake air temperature sensor
Failed air flow sensor
Failed injector
Failed engine coolant temperature sensor
Failed manifold absolute pressure sensor
Failed barometric pressure sensor
Incorrect fuel pressure
Failed engine-ECU

DIAGNOSIS PROCEDURE

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

Q. Is any other diagnosis code than P0172 stored?

	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 5: Intake air temperature sensor
Item 6: Engine coolant temperature sensor
Item 8: Manifold absolute pressure sensor
Item 10: Air flow sensor
Item BB: Barometric pressure sensor

Q. Are the check results normal?

	YES : Go to Step 3.

	Perform the diagnosis code classified check procedure for the sensor that has shown an abnormal data value. Inspection chart for diagnosis code (Refer to ).

STEP 3. Check injector itself.

Injector check (Refer to ).

Q. Is the check result normal?

	Go to Step 4.

	Replace the injector.

STEP 4. Fuel pressure measurement.

Fuel pressure test (Refer to ).

Q. Is the check result normal?

	Go to Step 5.

	Repair.

STEP 5. Replace the injector.

After replacing the injector, reconfirm whether the diagnosis code is stored.

Q. Is the diagnosis code stored?

	Replace the engine-ECU.

	Check end.